Question

The chance of getting a particular disease sometime during your lifetime is estimated at 1 in 20.

Smoking increases the risk of developing the disease during your lifetime by 20%.

How many people out of a group of 1000 smokers would you expect to get the disease sometime during their lifetime?

Answer 1

60 people

Explanation:

The chance of getting a particular disease is
`(1)/(20)`

To calculate how much the chance is increased by smoking, you have to calculate the 20% of
`(1)/(20)` and then perform the sum of it and the original chance

A 20% as a fractional number is
`(20)/(100)`

Therefore the 20% of
`(1)/(20)` is:

`((20)/(100) )((1)/(20)) = (1)/(100)`

So, the chance of getting a particular disease sometime during the lifetime for a smoker is:

`(1)/(20) + (1)/(100) = (6)/(100)`

This means that every 100 smokers, 6 of them would get the disease.

You have to multiply the risk by the group of smokers to calculate how many people you would expect to get the disease:

`(1000)((6)/(100)) = 60`

In conclusion, 60 people out of a group of 1000 people would get the disease.