Question

The systolic blood pressure of 60 patients attending a clinic was recorded as follows:
 

Blood Pressure	95-104	105-114	115-124	125-134	135-144	145-154	155-164
Number of patients	7	11	15	12	8	4	3

1. On the grid provided, draw an ogive that represents the above information.
2. Use the graph to estimate the interquartile range of the blood pressures.
3. Determine the percentage of patients whose blood pressure exceeds 150.

Answer 1

1. Table

   Class	f	cf	cf%
   95-104	7	7	11.67
   105-114	11	18	30.00
   115-124	15	33	55.00
   125-134	12	45	75.00
   135-144	8	53	88.33
   145-154	4	57	95.00
   155-164	3	60	100.00

   Graph
   
2.  Q₁ = 112.5 & Q₃ = 134.5
   Interquartile range =Q₃ − Q₁
   = 134.5 − 112.5
   = 22
3. more than 150→ 100% − 95% = 5%
   ∴ no = 5% x 60
   = 3