Question

A teen is dropped off at a mall and is asked to survey every twenty fifth person that walks out of the mall.

The situation above is an example of which sampling type? (2 points)

a	Stratified Random Sampling
b	Cluster Sampling
c	Systematic Sampling
d	Bivariate sampling

Considering the number of questions incorrect from classmates on a quiz {10, 11, 12, 13, 13, 13, 14, 15, 16, 16, 17, 18, 18, 19, 20}. According to the Empirical Rule, 68% of the data should fall between what two numbers? (2 points)

a	12 and 17
b	11.98 and 18.02
c	13.5 and 16.35
d	10.20 and 12.92

Question 23 (2 points)

A couple plans to have three children. The chance they have a girl is 0.8. The gender of one child is independent of the gender of another child. What is the probability of having two boys and one girl when having three children? (2 points)

a	0.008
b	0.096
c	0.384
d	0.512

Answer 1

1. It's an example of systematic sampling .

2. According to empirical nule of Normal distribution , 68% of the data lies within the one standard deviation boundary from its mean .  

For the above data mean = 15 sd = 3.02

So , 68% data should ;lie between ( 15- 3.02 , 15+3.02 ) = ( 11.98 , 18.02 )

3. Let G: giving birth to a girl B : gibing birth to a boy

So , P[G] = 0.8 , we can assume P[B] = 0.2

Three combinations are possible : { GBB , BGB , BBG }

each having probability = 0.8 x 0.2 x 0.2 = 0.032

So, required probability = 3 x 0.032 = 0.096