Question

Exam grades: Scores on a statistics final in a large class were normally distributed with a mean of 71 and a standard deviation of 8. Use the T1-84 PLUS calculator to answer the following. Round the answers to at least two decimals. (a) Find the 47 percentile of the scores (b) Find the 65 percentile of the scores. (c) The instructor wants to give an A to the students whose scores were in the top 12% of the class. What is the minimum score needed to get an A? (d) Between what two values are the middle 62% of the scores? (Enter the smaller number in the first box.) Part: 0/4 Part 1 of 4 Find the 47 percentile of the scores The 47" percentile of the scores is

Answer 1

use invnorm(perecntiile/100,0,1) function to get percentile value

a)

for 47th percentile critical value of z=		-0.08
therefore corresponding value=mean+z*std deviation=			70.40

b)

for 65th percentile critical value of z=		0.39
therefore corresponding value=mean+z*std deviation=			74.08

c)

for 88th percentile critical value of z=		1.17
therefore corresponding value=mean+z*std deviation=			80.40

d)as 62% middle values are between 19 and 81 percentile

corresponding values are: 63.98 and 78.02