Assume that when adults with smartphones are randomly selected, 5454% use them in meetings or classes. If 1515 adult smartphone users are randomly selected, find the probability that exactly 1010 of them use their smartphones in meetings or classes. The probability is

The probability is 0.1304 = 13.04%.

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 an adult using their smartphone in meetings or classes is independent of other adults. 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.

54% use them in meetings or classes.

This means that

If 15 adult smartphone users are randomly selected, find the probability that exactly 10 of them use their smartphones in meetings or classes.

This is P(X = 10) when n = 15. So

The probability is 0.1304 = 13.04%.

x= -3 and

step-by-step explanation:

to find the roots of a cubic, use division or factoring to find the factors then set equal to 0. as this is a difference of cubes, it factors into

where a is the cube root of .

here   this is 27 and the cube root of 27 is 3. so we write using the form:

.

set each factor to 0 and solve for x.

x-3=0

x=3

the quadratic expression does not factor and must be solved using the quadratic formula.

where a = 1, b=3, and c=9

this cubic has two complex roots.

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