Jacob spent half of his weekly allowance at the movies. To earn more money his parents let him wash the car for $7. What is his
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Answer:
The area of the shaded region is 0.9082.
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, which is the area of the shaded region, 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 problem, we have that:
Area of the shaded region:
pvalue of Z
has a pvalue of 0.9082
So
The area of the shaded region is 0.9082.
Answer:
Assuming ages are normally distributed, the 98% confidence interval for the population average age is [26.3, 35.7].
Step-by-step explanation:
We have to construct a 98% confidence interval for the mean.
The information we have is:
- Sample mean: 31
- Variance: 49
- Sample size: 15
- The age is normally distributed.
We know that the degrees of freedom are
Then, the t-value for a 98% CI is t=2.625 (according to the t-table).
The standard deviation can be estimated from the variance as:
The margin of error is:
Then, the CI can be constructed as: