Question

A mechanic finds that 30% of his customers own foreign cars, and that 40% own dogs. Assuming that these events are independent, what percent of the customers have neither a foreign car nor a dog

Answer 1

Since the events are independent, 30% of his customers have neither a foreign car nor a dog.

Explanation:

Let the total number of his customers = 100.

Since the events are independent,

customers with foreign cars + customers that own dogs + customers that have neither a foreign car nor a dog = 100.

But,

Customers with foreign cars = 30% = 30

Customers that own dogs = 40% = 40

Customers with neither foreign car nor dog = x%

So that,

30 + 40 + x = 100

70 + x = 100

x = 100 - 70

x = 30

Customers with neither foreign car nor dog = 30.

Converting this value to percentage,

=
`(30)/(100)` × 100

= 30%.

Therefore, 30% of his customers have neither a foreign car nor a dog.

Answer 2

42%

Explanation: