in a recent year, the scores for the reading portion of a test were normally dis
ID: 3318804 • Letter: I
Question
in a recent year, the scores for the reading portion of a test were normally distributed, with a mean of 20.4 and a standard deviati of 6 9 Complete parts (a) through (2) below (a) Find the probability that a randomly selected high school student who took the reading portion of the test has a score that is less than 17 The probability of a student scoring less than 17 is (Round to four decimal places as needed.) (b) Find the probablity that a randomly selected high school student who took the reading portion of the test has a score that is between 11.6 and 29.2 The probability of a student scoring between 1 1.6 and 29.26 Round to four decimal places as needed) (C) Find the probability that a randomly selected high school student who took the reading portion of the test has a score that is more than 34.3 The probability of a student scoring more than 343 is Round to four decimal places as needed.) (d) Identify any unusual events Explain your reasoning. Choose the correct answer below. A. The event in part (c) is unusual because its probabity is less than 0 05 B. The events in parts (a) and (D) are unusual because its probabilities are less than 0.05 C. The event in part (a) is unusual because its probabiuty is less than o D. None of the events are unusual because all the probab ites are greater than o os, Click to select your answer(s) 0o O Type here to search 7 4 5Explanation / Answer
Ans:
mean=20.4,std dev=6.9
a)
z(17)=(17-20.4)/6.9=-0.4928
P(z<-0.4928)=0.3111
b)
z(11.6)=(11.6-20.4)/6.9=-1.275
z(29.2)=(29.2-20.4)/6.9=1.275
P(-1.275<z<1.275)=P(z<1.275)-P(z<-1.275)
=0.8988-0.1012=0.7977
c)
z(34.3)=(34.3-20.4)/6.9=2.014
P(z>2.014)=0.0220
d)
Event in part (c) is unusual as its probabilty is less than 0.05.
Option A is correct.
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