# Frequency tables

1.

Grade,

x Freq Probability P(x) xP(x) (x-Âµ )sqP(x)

9 3604

10 3131

11 2749

12 2488

Total Âµ= sigma sq=

Determine the probability distribution of the randum varible x.

What is the probability taht a randomly selected student is either in the 9th or 10th grade?

What is the probability that a randomly selected student is in at most 11th grade?

Find the mean and standard deviation of the random variable x.

https://brainmass.com/statistics/frequency-distribution/frequency-tables-22973

#### Solution Preview

----------------------------------------------------------------------

<br>Determine the probability distribution of the random varible x.

<br>

<br>Total number of students = 11972

<br>P(x=9 ) = 3604/11972 = 0.30

<br>

<br>P(x=10) = 3131/11972 = 0.26

<br>

<br>P(x=11) = 2749/11972 = ...

#### Solution Summary

Grade,

x Freq Probability P(x) xP(x) (x-Âµ )sqP(x)

9 3604

10 3131

11 2749

12 2488

Total Âµ= sigma sq=

Determine the probability distribution of the randum varible x.

What is the probability taht a randomly selected student is either in the 9th or 10th grade?

What is the probability that a randomly selected student is in at most 11th grade?

Find the mean and standard deviation of the random variable x.