# Probability of baby girls in a test of a gender selection

In a test of a gender-selection technique, results consisted of 261 baby girls and 16 baby boys. Based on this result, what is the probability a girl born to a couple using this technique?

Does it appear that the technique is effective in increasing the likelihood that a baby will be a girl?

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#### Solution Preview

In a test of a gender-selection technique, results consisted of 261 baby girls and 16 baby boys. Based on this result, what is the probability a girl born to a couple using this technique?

Let p be the probability that a girl is born. Then, in a sample of 277 babies i.e. 261 + 16, the number of girls is binomially distributed.

Thus, the probability of 261 baby girls is given by:

C(277, 261) x p^261 x (1 - p)^16

here ^ means raised to the power of and C(277, 261) means 277 choose ...

#### Solution Summary

The expert calculates the probability of baby girls in a test of a gender selection. The technique effective in increasing the likelihood that the baby will be a girl is determined.