Question

Inclusive class intervals with respective boundaries are shown in the table below.

Limits	Boundaries
11-15	a-b
16-20	c-d

What is the sum of a, b, c and d?

• A. 31
• B. 63
• C. 62
• D. 72

Answer 1

The correct option is C 62

The average of the upper limit of thefirst class and the lower limit of the second class becomes the upper boundary of the first class.

And it also becomes the lower boundary of the second class.

So,

b = $\frac{15+16}{2}$ = 15.5
c = b = 15.5

Considering the upper limit of previous class of the first class as 10 we get,

a = $\frac{10+11}{2}$ = 10.5

Considering the lower limit of next of the second class as 21 we get,

d= $\frac{20+21}{2}$ = 20.5

Sum = 15.5 + 15.5 + 10.5 + 20.5 = 62