posted by Phyllis on .
A survey found 70% of adults over 50 wear glasses. In a random sample of 10 adults over 50, what is the probability that exactly six wear glasses and at least six wear glasses
The probability of all events occurring is found by multiplying the probabilities of the individual events.
.7^6 * .3^4 = ? (exactly six)
Add probabilities of 6, 7, 8, 9 and 10 for "at least."
e.g., for 10 wearing = .7^10 = ?
for 9 wearing = .7^9 * .3 =?
I'll let you do the remaining calculations.