Question

35% of North Americans do not think that college education is a contributory factor to economic success. A random sample of seven North Americans is selected. Find the probability that:
a. Exactly 3 people will agree with that position (taken by the 35% of the population)
b. At least 3 people will agree with the position
c. At most 5 people will agree with the position
d. Fewer than 4 people will agree with the position

Answer 1

a) prob (exactly3) = C(7,3) (.35)^3 (.65)^4
= .2679

b) at least 3 people
= 1 -(prob(none) + prob(one) + prob(two)
= 1 - ( C(7,0) .65^7 + C(7,1) (.35)(.65)^6 + C(7,2)(.35)^2 (.65)^5 )
= ..... you do the button pushing.

c) at most 5 ---- > 0,1,2,3,4,5
or exclude: 6 and 7

d) fewer than 4 ---> 0,1,2,3