Dan says he ran twice as far as karim what possiblities for the distance they each could run

16.78% probability that exactly 12 of them use their smartphones in meetings or classes.

Step-by-step explanation:

For each adult, there are only two possible outcomes. Either they use their smartphone in meetings or classes, or they do not. The probability of a person using their phone in meetings or classes is independent of any other person. So we use the binomial probability distribution to solve this question.

Binomial probability distribution

The binomial probability is the probability of exactly x successes on n repeated trials, and X can only have two outcomes.

In which is the number of different combinations of x objects from a set of n elements, given by the following formula.

And p is the probability of X happening.

64% use them in meetings or classes.

This means that

20 adult smartphone users are randomly selected

This means that

Probability that exactly 12 of them use their smartphones in meetings or classes.

This is P(X = 12).

16.78% probability that exactly 12 of them use their smartphones in meetings or classes.