Aleks help find y and z
1 answer:
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Answer:
The proportion of children in this age range between 70 lbs and 85 lbs is of 0.9306.
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.
A study suggested that children between the ages of 6 and 11 in the US have an average weightof 74 lbs, with a standard deviation of 2.7 lbs.
This means that
What proportion of childrenin this age range between 70 lbs and 85 lbs.
This is the pvalue of Z when X = 85 subtracted by the pvalue of Z when X = 70. So
X = 85
has a pvalue of 1
X = 70
has a pvalue of 0.0694
1 - 0.0694 = 0.9306
The proportion of children in this age range between 70 lbs and 85 lbs is of 0.9306.
We have been given that Tim spends about 1/3 of each weekday sleeping and about 7/24 of each weekday in school. And we need to find what fraction of the weekday does Tim spend either sleeping or in school.
This means that we need to find the time he spends in sleeping when he is in the school.
Therefore, we have to add the time he spends in sleeping and the time he spends in school.
Therefore, required fraction is given by
Now in order to add the fractions, we have to make the denominator same.
Multiply the numerator and denominator of first fraction by 8 to make the same denominator.
Now, we have the same denominator hence, we can add the numerator
Therefore, Tim spends 15/24 hours each weekday sleeping in the school.