Answer:
The standard deviation of the age of the customers was of 2.08 years.
Step-by-step explanation:
Problems of normally distributed samples can be 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:
85% of the customers are between the ages of 21 and 27 years.
Since the normal distribution is symmetric, this means, for example, that 27 is the 50 + (85/2) = 92.5th percentile, that is, when , Z has a pvalue of 0.925. So when . We use this to find
The standard deviation of the age of the customers was of 2.08 years.
1% of $40 = $0.4
8% of $40 = $0.4 x 8 = $3.2
Total = $43.20
Answer:
x = 39
Step-by-step explanation:
there is a theorem that states that the midsegment in a trapezoid is equal to the sum of the bases divided by two
so, (36 + 42)/2 = x
36 + 42 = 78
78/2 = 39
Answer:
Other root:
Step-by-step explanation:
If , then .
Therefore:
This means that the other root is since