A normal distribution has a mean of 10 and a standard deviation of 1. What is the probability of selecting a
number that is at most 9?

15.87% probability of selecting a number that is at most 9

Step-by-step explanation:

When the distribution is normal, we use the z-score formula.

In a set with mean and standard deviation , the zscore of a measure X is given by:

The Z-score measures how many standard deviations the measure is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the pvalue, we get the probability that the value of the measure is greater than X.

In this question, we have that:

What is the probability of selecting a number that is at most 9?

This is the pvalue of Z when X = 9. So

has a pvalue of 0.1587

15.87% probability of selecting a number that is at most 9

answer: the anser is 3

step-by-step explanation:

c- 2o is equal to 9

n=9

step-by-step explanation:

7 times a number = 7n

decreased by 13 = 7n-13

same as is =

5 times the number = 5n

increased by 5 = 5n+5

7n-13 = 5n+5

2n=18

n=9