MATHEMATICS
PAPER 2
Instructions to candidates
- This paper consists of TWO sections. Section A and Section B.
- Answer ALL the questions in section A and only FIVE questions from Section B.
- Show all the steps in your calculations, giving your answers at each stage in the spaces below each question.
- Marks may be given for correct working even if the answer is wrong.
- Non-programmable silent calculators and KNEC mathematical tables may be used except where stated otherwise.
Questions
- Make x the subject of the formula. (3mks)
- Simplify the following by rationalizing the denominator. (3mks)
8
4-2√3 - A quantity P is partly constant and partly varies inversely as square of t. p =6 when t=6 and p=18 when t=3. Find t when p=11. (3mks)
- Solve for x in the equation; (3mks)
Log8(x+6) – log8(x-3) = 2/3 - In the figure below QT is a tangent to a circle at Q. PXRT and QXS are straight lines. PX =6cm, RT=8cm, Qx=4.8cm and Xs= 5cm.
Find the length of;- XR (2mks)
- QT (2mks)
- Solve for x and y in the simultaneous equation below. (3mks)
xy + 6= 0
x - 2y= 7 - Solve for x. (3mks)
2x2+x-36= 0 - Expand (1+2x)7 up to the term in x3, hence use the expansion to estimate the value of (1.02)7 correct to four decimal places. (3mks)
- Find the value of y for which is a singular matrix. (3mks)
-
- Find the inverse of the matrix . (1mk)
- Hence solve the simultaneous equation using the matrix method. (3mks)
4x+3y =6
3x+5y =5
- An item that costs sh. 24, 000 cash can be bought on hire purchase. A customer pays sh.6, 000 as deposit and then makes 6 monthly installments of sh.3, 500 each. Calculate the monthly rate of compound interest, giving your answer to 1 d.p. (3mks)
- Barasa shared sh.360, 000 among his children Simiyu, Wasike and Nekesa I the ratio 1:3:5 respectively. How much did each receive? (3mks)
- In the arithmetic series 1+4+7+10+…find the sum of the first 100 terms. (3mks)
- If , and . find 3a-2b+c. (3mks)
- Make x the subject (3mks)
- The figure below shows a triangle xyz in which x=13.4cm, z=5cm and ˂xyz= 57.70. Find length y. (3mks)
SECTION B: ANSWER 5 QUESTIONS ONLY IN THIS SECTION.
-
- Complete the table below for the function y=2x2+3x-5
x -4 -3 -2 -1 0 1 2 2x2 0 3x -12 18 -5 -5 -3 6 y - On the grid provided draw the graph of y=2x2+3x-5 for -4≤x≤2. (4mks)
- Use your graph to state the roots of
- 2x2+3x-5=0 (1mk)
- 2x2+6x-2=0 (3mks)
- Complete the table below for the function y=2x2+3x-5
- A trader bought 8 cows and 12 goats for a total of ksh.294, 000. If he had bought 1 more cow and 3 more goats he would have spend ksh.337, 500.
- Form two equations to represent the above information. (2mks)
- Use matrix method to determine the cost of a cow and that of a goat. (3mks)
- The trader sold the animals he had bought making a profit of 40% per cow and 45% per goat.
- Calculate the total amount of money he received. (3mks)
- Determine his profit in Kenyan shillings. (2mks)
- The bearing of towns P and Q on a horizontal ground from a tower are 050 and 142 respectively. The angle of elevation of the top of the lower from town P is 34 . Given that P is 200m from the top of the tower and Q is 120m from the base of the tower
Determine- The height of the tower (3mks)
- The angle of elevation of the top of the lower from Q (3mks)
- The distance between the two towns P and Q (4mks)
- A group of young men decided to raise ksh.480, 000 to start a business. Before actual payment was made four members pulled out and each of the remaining had to pay an additional ksh.20,000 write an expression in terms of p for;
-
- Original contribution of each member. (1mk)
- Contribution after withdrawal of four members. (1mk)
- Form an equation in p and hence determine the number of initial members. (5mks)
- Three men Kamau, James and Hassan shared shs.480, 000 such that Kamau: James is 3:2 and James:Hassan is 4:2. Find how much each got. (3mks)
-
- The relationship between two variables S and T is given by the equation S=KTn where K and n are constant
- Write down the linear equation relating to S and T (1mk)
- Complete the table above for the linear equation relating to S and T(to one decimal place) (2mks)
- Draw a suitable straight line graph to represent the data (3mks)
- Use your graph to determine the value of K and n (2mks)
- Find the value of S when T =3.5 (2mks)
-
- The current price of a vehicle is shs 500,000. If the vehicle depreciates at a rate of 15% p.a . Find the number of years it will take for its value to fall to shs 180,000. (4mks)
- The cash price of a cooker is shs 9,000. A customer bought the cooker by paying 15 monthly installments of shs 950 each. Calculate:
- the carrying charge (3mks)
- the rate of interest (3mks)
- The table below shows the income tax rates in a certain year.
Mrs Musau earned a basic salary of ksh 18,600 per month and allowances amounting to ksh.7, 800 per month. She claimed a personal relief of ksh 1,080 per month. Calculate;- Total taxable income in k£ p.a. (2mks)
-
- The tax payable in ksh per month without relief. (4mks)
- The tax payable in ksh per month after relief. (2mks)
- Mrs Musau’s net monthly income. (2mks)
- The probability that boys goes to school by bus is 1/3 and by matatu is 1/2. If he uses a bus the probability that he is late to school is 1/5 and if he uses a matatu the probability of being late is 3/10. If he uses other means of transport, the probability of being late is 1/20. What is the probability that
- He will be late to school
- He will not be late to school
- He will be late to school if he does not use a matatu
- He neither uses a bus nor matatu but arrives to school early.
Marking Scheme
- Make x the subject of the formula. (3mks)
- P2= x + 2w
4x +3R
P2(4x+3R) = x + 2w
P24x + P23R = x + 2w
4P2x-x = 2w - P23R
x(4P² - 1) = 2w - 3P²R
4P² - 1 4P² - 1
x = 2w - 3P²R
4P²-1
- P2= x + 2w
- Simplify the following by rationalizing the denominator. (3mks)
8
4-2√3- 8 (4 + 2√3)
4-2√3 (4 + 2√3)
8 x 2(2 + √3 )
16 - 12
16(2 + √3)
4
8(2 + √3)
16 + 8√3
- 8 (4 + 2√3)
- A quantity P is partly constant and partly varies inversely as square of t. p =6 when t=6 and p=18 when t=3. Find t when p=11. (3mks)
- p= a + b/t2
6 = a + b/36
216 = 36a+b
216=36a+b
18=a+b/a
162= 9a+b
36 a+b=216
-4a + b = 162
27a = 54
a=2
9a + b = 162
18 + b = 162
b= 162 -18
b=144
P= 2 + 144/t2
11= 2 + 144/t2
9= 144/t2
9t² = 144
9 9
t=√144/9
t= 12/3
= ±4
- p= a + b/t2
- Solve for x in the equation; (3mks)
Log8(x+6) – log8(x-3) = 2/3
- Log8(x+6) – log8(x-3) = Log88²/₃
Log8(x+6/x-3) = Log8 4
x + 6 = 4
x-3
x+6 = 4x-12
18 = 3x
3 3
6=x
- Log8(x+6) – log8(x-3) = Log88²/₃
- In the figure below QT is a tangent to a circle at Q. PXRT and QXS are straight lines. PX =6cm, RT=8cm, Qx=4.8cm and Xs= 5cm.
Find the length of;- XR (2mks)
- 6x = 4.8 x 5
x= 4.8 x 5
6
x=4cm
- 6x = 4.8 x 5
- QT (2mks)
- QT2 = PT.RT
QT2= 18.8
QT2=144
QT=±12
+12
- QT2 = PT.RT
- XR (2mks)
- Solve for x and y in the simultaneous equation below. (3mks)
xy + 6= 0
x - 2y= 7- x= 7 + 2y
y(7 + 2y) + 6 =0
7y + 2y2 + 6 =0
2y2 + 7y + 6 =0
s=2
p=12
F=423
2y2 + 4y + 3y + 6=0
2y(y+2) +3(y+2) =0
(2y+3)(y+2)=0
2y=-3 y=-2
y= -3/2
x= 7+2y
x=7+2(-2)
x=3
x=7+2(-3/2)
x=7+-3
x=4
- x= 7 + 2y
- Solve for x. (3mks)
2x2+x-36= 0- 2x2+x-36=0
s=1
p= -72
F=9.8
2x2 + 9x - 8x - 36 = 0
x(2x+9)-4(2x+9)=0
(x-4)(2x+9)=0
x-4
2x =-9
x=-4.5
- 2x2+x-36=0
- Expand (1+2x)7 up to the term in x3, hence use the expansion to estimate the value of (1.02)7 correct to four decimal places. (3mks)
- (1+2x)2
1 7 21 35 35 12 16 15 14 13 (2x)° (2x) (2x)2 (2x)3
1 + 14x + 84x2 + 280x3
1 + 14x + 84x2 + 280x3 + ...
(1.02)2 →(1 + 0.02)7
(1 + 2x)7
2x=0.02
2 2
x=0.01
1 + 14(0.01) + 84(0.01)2 + 280(0.01)3
1+ 0.14 + 0.0084 + 0.00028
1.14868
- (1+2x)2
- Find the value of y for which is a singular matrix. (3mks)
- 18-4y=0
18=4y
4 4
45 =y
- 18-4y=0
-
- Find the inverse of the matrix . (1mk)
- 20 - 9 = 11
- 20 - 9 = 11
- Hence solve the simultaneous equation using the matrix method. (3mks)
4x+3y =6
3x+5y =5
x- 30/11 - 15/11 → 15/11
y= -18/11 x 20/11 → 2/11
- Find the inverse of the matrix . (1mk)
- An item that costs sh. 24, 000 cash can be bought on hire purchase. A customer pays sh.6, 000 as deposit and then makes 6 monthly installments of sh.3, 500 each. Calculate the monthly rate of compound interest, giving your answer to 1 d.p. (3mks)
- A = P(1 + r/100)n
27000 = 24000 (1 + r/100)6
(1 + r/100)6 = 27000/24000
n= 6 months
√(1 + 1/100)6 = 6√1.125
≈ 1.02 to 2d.p
r/100 = 1.02 -1
r/100 = 0.02
r= 2%
- A = P(1 + r/100)n
- Barasa shared sh.360, 000 among his children Simiyu, Wasike and Nekesa I the ratio 1:3:5 respectively. How much did each receive? (3mks)
- 1/9 x 360000 = 40000
3/9 x 360000 = 120000
5/9 x 360000= 200000
- 1/9 x 360000 = 40000
- In the arithmetic series 1+4+7+10+…find the sum of the first 100 terms. (3mks)
- sn = n/2(2a + (n-1)d)
s100 = 100/2 ( 2 + 99x3)
= 14,950
- sn = n/2(2a + (n-1)d)
- If , and . find 3a-2b+c. (3mks)
-
- Make x the subject (3mks)
- P3 = bx² - ax
x
P3 = x(bx - a)
x
P3 = bx - a
P3 + a = bx
P³ + a = x
b
- P3 = bx² - ax
- The figure below shows a triangle xyz in which x=13.4cm, z=5cm and ˂xyz= 57.70. Find length y. (3mks)
y2 = x2 + 22 - 2 x 2 Cos 57.7°
y2 = 1342 + 52 - 2 x 134.5 Cos 57.7°
y2 = 179.56 + 25 - 134Cos 57.7°
y2= 204.56 - 134 x 0.5344
y2 = 204.56 - 71.6096
y2 = √132.9504
y= ±11.53
SECTION B: ANSWER 5 QUESTIONS ONLY IN THIS SECTION.
-
- Complete the table below for the function y=2x2+3x-5
x -4 -3 -2 -1 0 1 2 2x2 32 18 8 2 0 2 8 3x -12 -9 -6 -3 0 3 6 -5 -5 -5 -5 -5 -5 -5 -5 y 15 4 -3 -6 -5 0 9 - On the grid provided draw the graph of y=2x2+3x-5 for -4≤x≤2. (4mks)
- Use your graph to state the roots of
- 2x2+3x-5=0 (1mk)
- 2x2+6x-2=0 (3mks)
- y=0 x=1 or x=-2.5
2x2 + 6x -2 = y
2x2 + 3x -5=0
3x + 3=y
x 0 1 -1 y 3 6 0
x=-2 or 1.9
- y=0 x=1 or x=-2.5
- Complete the table below for the function y=2x2+3x-5
- A trader bought 8 cows and 12 goats for a total of ksh.294, 000. If he had bought 1 more cow and 3 more goats he would have spend ksh.337, 500.
- Form two equations to represent the above information. (2mks)
- 8x + 12y = 294000
9x + 15y= 337500
4x + 6y = 147000
3x + 5y = 112500
- 8x + 12y = 294000
- Use matrix method to determine the cost of a cow and that of a goat. (3mks)
-
367500+ - 337500
x= 30000
-220500 + 225000
y= 4500
-
- The trader sold the animals he had bought making a profit of 40% per cow and 45% per goat.
- Calculate the total amount of money he received. (3mks)
- 40/100 x 30000
Profit 12000
45/100 x 4500
= 2025
42000 x 8 + 12 x 6525
336000 + 78300
= 414300
- 40/100 x 30000
- Determine his profit in Kenyan shillings. (2mks)
- 414300 - 294000 =120300
- 414300 - 294000 =120300
- Calculate the total amount of money he received. (3mks)
- Form two equations to represent the above information. (2mks)
- The bearing of towns P and Q on a horizontal ground from a tower are 050 and 142 respectively. The angle of elevation of the top of the lower from town P is 34 . Given that P is 200m from the top of the tower and Q is 120m from the base of the tower
Determine- The height of the tower (3mks)
- The angle of elevation of the top of the lower from Q (3mks)
- The distance between the two towns P and Q (4mks)
- A group of young men decided to raise ksh.480, 000 to start a business. Before actual payment was made four members pulled out and each of the remaining had to pay an additional ksh.20,000 write an expression in terms of p for;
-
- Original contribution of each member. (1mk)
- 480000
p
- 480000
- Contribution after withdrawal of four members. (1mk)
- 480000 + 20000
p -4
- 480000 + 20000
- Original contribution of each member. (1mk)
- Form an equation in p and hence determine the number of initial members. (5mks)
- 480000 - 480000 = 20000
p p-4
480000(p-4) - 480000p = 20000(p)(p-4)
480,000p - 1920000 - 480000p = 20000p2 - 80000p
-1920000 = 20000p2 - 80000p
10,000(-192) = 10,000(2p2 - 8p)
-192 = 2p2 - 8p
-96 = p2 - 4p
p2 - 4p + 96 = 0
4± √(42 - 4x1x - 96)
2
4 ± 20
2
xd = 24/2 =12
- 480000 - 480000 = 20000
- Three men Kamau, James and Hassan shared shs.480, 000 such that Kamau: James is 3:2 and James:Hassan is 4:2. Find how much each got. (3mks)
- K:J:H
3:2
4:2
6:4:2
6/12 x 480,000 = 240,000
4/12 x 480,000 = 160,000
2/12 x 480,000 = 80,000
- K:J:H
-
- The relationship between two variables S and T is given by the equation S=KTn where K and n are constant
- Write down the linear equation relating to S and T (1mk)
- Complete the table above for the linear equation relating to S and T(to one decimal place) (2mks)
- Draw a suitable straight line graph to represent the data (3mks)
- Use your graph to determine the value of K and n (2mks)
- Find the value of S when T =3.5 (2mks)
-
- The current price of a vehicle is shs 500,000. If the vehicle depreciates at a rate of 15% p.a . Find the number of years it will take for its value to fall to shs 180,000. (4mks)
- The cash price of a cooker is shs 9,000. A customer bought the cooker by paying 15 monthly installments of shs 950 each. Calculate:
- the carrying charge (3mks)
- the rate of interest (3mks)
- The table below shows the income tax rates in a certain year.
Mrs Musau earned a basic salary of ksh 18,600 per month and allowances amounting to ksh.7, 800 per month. She claimed a personal relief of ksh 1,080 per month. Calculate;- Total taxable income in k£ p.a. (2mks)
- 18,600
+7,800
26 400
26400 x 12 = 316800
20 20
£15,840
- 18,600
-
- The tax payable in ksh per month without relief. (4mks)
- 3900 x 2 = 7,800
- 3900 x 3 = 11,700
- 3900 x 4 = 15,600
- 3900 x 5 = 19,500
- 240 x 7 = 1680
- 56,280 = 4,690
12
- The tax payable in ksh per month after relief. (2mks)
- 4690
1080
3610
- 4690
- The tax payable in ksh per month without relief. (4mks)
- Mrs Musau’s net monthly income. (2mks)
- 26400
3610
22790
- 26400
- Total taxable income in k£ p.a. (2mks)
- The probability that boys goes to school by bus is 1/3 and by matatu is 1/2. If he uses a bus the probability that he is late to school is 1/5 and if he uses a matatu the probability of being late is 3/10. If he uses other means of transport, the probability of being late is 1/20. What is the probability that
- He will be late to school
-
- (1/3 x 1/5)+(1/2 x 3/10)+(1/6 x 1/20)
1/15 + 3/20 + 1/120
= 8 +18 + 1
120
27/120 = 9/40
-
- He will not be late to school
- (1/3 x 4/5)+(1/2 x 7/10)+(1/6 x 19/20)=
4/15 + 7/20 + 19/120
= 32 + 42 + 19
120
=93/120
- (1/3 x 4/5)+(1/2 x 7/10)+(1/6 x 19/20)=
- He will be late to school if he does not use a matatu
- (1/3 x 1/5)+(1/6 x 1/20)
1/15 + 1/120
8 + 1
120
=9/120
- (1/3 x 1/5)+(1/6 x 1/20)
- He neither uses a bus nor matatu but arrives to school early.
- 1/6 x 19/20 = 19/20
- He will be late to school
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