Question 1132664
i would think it would be the probability of having exactly 3 plus exactly 4 plus exactly 5 or more.
that would be equal to 15 + 5 + 3 = 23%.


to test this out, assume 100 families that fit the proportions shown.
55 would have one child under 21.
22 would have two children under 21.
15 would have three children under 21.
5 would have four children under 21.
3 would have 5 or more children under the age of 21.


count up the families that have 3 or more children under 21 and you get 15 + 5 + 3 = 23.


if you pick a family out of the 100 at random, 23 times out of 100 you will get a family that has at least 3 children.


that's a probability of 23%.