# Mathematics Tutors

 Subject Mathematics Due By (Pacific Time) 12/02/2016 12:00 am

1 Find Probabilities for Normally Distributed Variables
9) IQ test scores are normally distributed with a mean of 100 and a standard deviation of 15. An individualÊ¹s IQ score is found to be 110. Find the z-score corresponding to this value.
A) 0.67 B) -0.67 C) 1.33 D) -1.33

10) IQ test scores are normally distributed with a mean of 100 and a standard deviation of 15. An individualÊ¹s IQ
score is found to be 120. Find the z-score corresponding to this value.
A) 1.33 B) -0.67 C) 0.67 D) -1.33

11) The lengths of pregnancies of humans are normally distributed with a mean of 268 days and a standard deviation of 15 days. Find the probability of a pregnancy lasting less than 250 days.
A) 0.0606 B) 0.1591 C) 0.1151  D) 0.0066

12) An airline knows from experience that the distribution of the number of suitcases that get lost each week on a certain route is approximately normal with μ = 15.5 and σ = 3.6. What is the probability that during a given week the airline will lose less than 20 suitcases?
A) 0.3944 B) 0.8944  C) 0.1056 D) 0.4040
5.3 Normal Distributions: Finding Values
1 Find a z-score Given the Area Under the Normal Curve

13) Find the z-scores for which 90% of the distribution’s area lies between -z and z.
A) (-1.645, 1.645)
B) (-2.33, 2.33)
C) (-1.96, 1.96)
D) (-0.99, 0.99)
3 Use Normal Distributions to Answer Questions

14) The scores on a mathematics exam have a mean of 77 and a standard deviation of 8. Find the x-value that corresponds to the z-score 2.575.
A) 56.4 B) 97.6  C) 85.0 D) 79.6

15) Assume that the heights of women are normally distributed with a mean of 63.5 inches and a standard deviation of 2.5 inches. Find Q3, the third quartile that separates the bottom 75% from the top 25%.
A) 65.2 B) 61.8 C) 66.4 D) 66.7

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