An on-line poll found that 35% of all married couples do not buy each other birthday gifts. Based on this information, what is the probability that for a random sample of 10 married couples, 4 do not buy each other birthday gifts?

0.24

Step-by-step explanation:

This is a form of a Bernoulli trial problem.

The probability of finding a couple that do not buy gift for each other is 35/100 = 0.35

The probability of finding a couple who are gift buyers is 1 - 0.35 = 0.65

Now to compute the probability, by using the Bernoulli trial:

P (4) = nCr (p) ^n (q) ^n - 1

P (4) = 10C4 * 0.35^4 * 0.65^6

P = 0.24