Testing a Claim about Population Proportion

In the natural populations of Trinidadian guppies, females select the males with orange coloration for mating.

To determine if guppy populations in an aquarium also show the same behavior, an experiment is conducted where 12 females are individually introduced to three orange males and three blue males simultaneously.

It is originally claimed that the females choose the orange males.

So, the null hypothesis would state that an equal number of females would show a preference for orange and blue males. The alternative hypothesis is that a higher number of females would prefer the orange males.

The experiment shows that ten out of twelve females preferred the orange males.

This ratio provides the sample proportion— 0.83—which is used to get the test statistic as follows.

It is observed that this test statistic falls within the critical region at a significance level of 0.05.

Also, the P-value from this z statistic is 0.011.

So, we may conclude that the aquarium population of guppies shows the same mating preference as observed in the natural population.