9) The mean length of a human pregnancy is 265 days, with a standard deviation o

Question

9) The mean length of a human pregnancy is 265 days, with a standard deviation of 10 days Use the Empirical Rule to determine the percentage of women whose pregnancies are betv days. (Assume the data set has a bell-shaped distribution.) A) 95% B) 68% C) 99.7% D) 50% 10) The test scores of 30 students are listed below. Find the five-number summary. 10) 31 41 45 48 52 55 56 58 63 65 67 67 69 70 70 74 75 78 79 79 80 81 83 85 85 87 90 92 95 99 A)Min-31,Q1 = 58, Q2 = 7o, Q3-83, Max-99 B) Min-31, Q1 = 57, Q2-70, Q3-81, Max = 99 C)Min = 31, Q1-58, Q2 = 72, Q3-83, Max = 99 D) Min = 31, Qi-57, Q2° 72, Q3 : 81, Max 99 11) Find the z-score for the value 55, when the mean is 58 and the standard deviation is 3 B) z =-1.33 C)2=-1.00 D) z = 0.90 A)z0.90 12) C) 0.5 D) 0.1 A) 0.333 B) 0.25 13 13) card is drawn from a standard deck of 52 playing cards, what is the probability of drawing· heart? C) 1 Dy A) B) 14) A question has five multiple-choice answers. Find the probability of guessing an incorrect answer D) B) C) A)

Explanation / Answer

9)

P(255<u<275)

Z= (x-u)/

z1 = (255-265)/10 = -1

z2 = (275-265)/10 = 1

Thus, P(255<z<275) = P(-1<z<1)

= 0.8413 - 0.1587 = 0.6826

= 68%

10)

total terms = 30

Min = 31, Max =99,

Q2 = (15th + 16th)/2 = (70+74)/2 = 72

Q1 = 8th term = 58

Q3 = 23rd term = 83

Option C

11)

Z= (x-u)/

= (55-58)/3 = -1

Option C

12)

P(rolling number less than 3)

= rolling 1,2 from 1,2,3,4,5,6

Thus, required probability = 2/6 = 0.333

Option A

13)

Total cards =52

Total hearts = 13

P(heart) = 13/52 = 1/4

Option B

14)

P(incorrect answer) = total wrong answers /total answers

= 4/5

Option B

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