Question

Please Help With My Math Homework...?

A school knows 84% of its incoming students owns a smartphone and 38% own a smartphone and a tablet. Find the probability that given a student owns a smartphone, they also own a tablet

A.) 32%
B.) 38%
C.) 45%
D.) 51%

Answer 1

C) `45`%

Explanation:

One way to think about this is to suppose that the intake is exactly `100` students.

Then exactly `84` of those students own a smartphone and `38` own both a smartphone and tablet.

The `38` students all own smartphones so are amongst the `84`.

So ignoring the `16` students who own no smartphone, the probability that one of the `84` students owns a tablet is:

`38/84 ~~ 0.45238`

As a percentage ("per-cent-age" i.e. "per-hundred-age"), multiply by `100` to get:

`0.45238 * 100 = 45.238 ~~ 45`

More generally, we can observe that the conditional probability of `A nn B` given `A` is simply:

`(P(A nn B)) / (P(A))`