Question

In a survey of 100 people, some of them jog for exercise, some of them ride a bike, some do both, and 15 do not jog or ride a bike. If 46 of the people surveyed job and 21 of them both jog and ride a bike, how many of the people surveyed only ride a bike?

Answer 1

Bike alone = 39

Explanation:

Given that:

Total number = n(T) = 100

Jog= n(J)

Bike = n(B)

Bike and jog = n(BnJ) = 21

Number who jog = 46

Jog alone = 46 - 21 = 25

Neither jog nor bike = 15

Let bike alone = x

Hence,

Jog alone + bike alone + jog and bike + none of the two = 100

25 + x + 21 + 15 = 100

x = 39