Step-by-step explanation:
a. First, find the z-score.
z = (x − μ) / σ
z = (80 − 74.0) / 12.5
z = 0.48
Use a calculator or table to find the probability.
P(z < 0.48) = 0.6844
b. Find the standard deviation of the sample.
σₓ = σ / √n
σₓ = 12.5 / √4
σₓ = 6.25
Find the z-score.
z = (x − μ) / σ
z = (80 − 74.0) / 6.25
z = 0.96
Use a calculator or table to find the probability.
P(z < 0.96) = 0.8315
c. When the distribution of the population is normal, then the distribution of the sample mean is also normal.
Answer:
19.77% of average city temperatures are higher than that of Cairo
Step-by-step explanation:
Problems of normally distributed samples are solved using 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 percentage of average city temperatures are higher than that of Cairo?
This is 1 subtracted by the pvalue of Z when X = 21.4.



has a pvalue of 0.8023
1 - 0.8023 = 0.1977
19.77% of average city temperatures are higher than that of Cairo
Answer:
b. 50 degrees
Step-by-step explanation:
Answer:
This is an english server.
Step-by-step explanation: