Question

a It is estimated that a nuclear bomb similar to the bomb dropped by the
USA over the Japanese city of Hiroshima during the Second World War
would kill everyone over an area of 8.92 km2
.
It is also estimated that the USA and Russia possess 13 200 nuclear
warheads between them.
The area of inhabited land on earth is estimated to be around
4 449 780 km2
.What percentage of the area of the earth would be affected if all nuclear
warheads owned by the USA and Russia were launched together?

Answer 1

One average a bomb destroys 8.92 km². 13200 such bombs ruin

$$A=8.92\cdot13200=117744\text{ km}^2.$$

This is

$$\frac{A}{A_\text{Earth}}\cdot100\%=\frac{117744}{4 449 780}\cdot100\% =2.65\%$$

of the inhabited land.