molsen
Jun 3, 2007, 04:00 PM
statistics canada reported that approx. 76% of families in a city consist of married couples. Tehre are 22 students in a grade 3 class.
what is the probability that exactly half the students have families where the parents are defined as a married couple?
I have:
n=22
p=0.76 (probability of married couples)
q=0.24 (probability of non-married couples)
____________
standard deviation=\/ 22*0.76*0.24
= 2.00
I found the z-score which was:
z= (11-16.7) / 2.00 = -2.85
and from the table of z-scores I found the answer to be 0.0183 or 1.8%
is this right, or where did I go wrong?
there is a second part to the questions that asks for the probability that at least one student does not have parents that are defined as a married couple that I am having trouble starting as well.
what is the probability that exactly half the students have families where the parents are defined as a married couple?
I have:
n=22
p=0.76 (probability of married couples)
q=0.24 (probability of non-married couples)
____________
standard deviation=\/ 22*0.76*0.24
= 2.00
I found the z-score which was:
z= (11-16.7) / 2.00 = -2.85
and from the table of z-scores I found the answer to be 0.0183 or 1.8%
is this right, or where did I go wrong?
there is a second part to the questions that asks for the probability that at least one student does not have parents that are defined as a married couple that I am having trouble starting as well.