Solution:
As per the problem
A person is born every 5 seconds and a person dies every 12 seconds.
Here the LCD of 5 and 12 is 60.
The number of person born in 60 seconds
The Number of person died in 12 seconds
Hence Population increase in 60 seconds is
Hence time required to increase the population by one 
1 hour = 3600 seconds
3 × 3600 = 10800
<span>10800 yards per hour
</span>
1 mile = 1760 yards
10800 ÷ 1760 = 6.13
6.13 miles per hour
7.
7 squared gives 49, and it is a prime number.