Question

After having a​ sonogram, a pregnant woman learns that she will have twins. What is the probability that she will have identical​ twins?

Answer 1

`(1)/(7)`

Explanation:

The table containing information about the sexes of twins and and the type of twins are given in the table below with corresponding weightage.

Now, since we know that she is expecting twins, the probability of the event

`A - '\text{the woman will have identical twins }'`

is calculated as follows

`Pr(A) = \frac{\text{total number of boy/boy, boy/girl, girl/boy and girl/girl identical twins}}{\text{total number of both identical and frathernal twins}}`

By using the informations from the given table, we obtain

`Pr(A) = (2 + 0 + 0 +2)/(28) = (4)/(28) = (1)/(7)`