Question

Define the random variable $X.$

Short answer

$X$be the number of days in a week that Ellen has music training.

Step-by-step solution

Given Information

Ellen has music practice three days a week, all three days are chosen at random$85$ percent of the time, two days are chosen at random $8$ percent of the time, one day is chosen at random $4$ percent of the time, and no days are chosen at random $3$percent of the time.

Concept Used

A random variable depicts the problem's features, and we'll call $X$ the number of days Ellen has music training in a week.

According to discrete distribution properties,

The probability mass function of a discrete variable$X$ is known as$P\left(X\right)$.

i. $P\left(X\right)\ge 0$for all X

ii.$\sum P\left(X\right)=1$

Explanation & conclusion

As a result, let$X$represent the number of days Ellen performs music in a week.