How to find a side in a right triangle with given hypotenuse?

You need to know  more information, not just the length of the hypotenuse.

If you know the length of one leg  use Pythagoras theorem to find the other.

If you know the value of one other angle  use trigononemtry

No, I don't believe that percent of girls born in china is 46.7.

Step-by-step explanation:

Given

Natural ratio of girls to boy =100:105

In China , the birth ratio = 100:114

Number of girls=46.7%

In our study

Number of girls=60

Number of boys= 90

Total number of birth =150

To find the percentage of girls in our study

Percentage of girls=40%

Therefore, the percentage of girls in our study is 40% not 46.7%

Hence, I don't believe that percentage of girls born in China is 46.7%.