doubts...pls help

[SoniaKapoor]

q1 The distribution of the heights of students in a large class is roughly bell shaped. Moreover,
the average height is 68 inches, and approximately 95% of the heights are between 62 and 74
inches. What is the standard deviation of the height distribution approximately?
a) 2 c) 6
b) 3 d) 9

q2 Find no of ways in which two books on economics and three books on accountancy can be
arranged in a line.
a) 60 c) 24
b) 120 d) 40

q3 The standard deviation of a group of scores is 10. If 5 were subtracted from each score, what
would be the standard deviation of the new scores?
a) 2 c) 5
b) 10/25 d) None of these

[Granpa Simpson]

Q2) 120 ways.
Q3) None of these.
Q1) u can derive the limits and compute the sd.

[Anjali]

For 2 , 120 ways
For 3 the standard deviation will remain the same

[Anjali]

Which means d for ques 3

[Homer Simpson]

1)(b)

P(62<x<74) = 0.95
    Z-SCORE = 1.96

to find s.d -

- 1.96 = (62 - 68)/s
or, 1.96 = (74 - 68)s

=> s is approximately 3

2(b) 5!
3(d) SD independent of change in origin

[Dreyfus]

A1. SD ~ 3
A.3 10 ie none of these

[Granpa Simpson]

For Q2) 5! ways

[SoniaKapoor]

thanku all of u:)