# Math Help - Double Check Please

1. ## Double Check Please

can someone check if the answer is right?

suppose that $1$ in every $10^7$ stars orbited by an earth-like planet:

a) if there are $100 x 10^9$ stars in the milky way galaxy, how many of its planets are earthlike?

b) if there are $100x10^9$ galaxies in the universe, how many of its planets are earth-like?
for a) I divided $100x10^9$ by $10^7$ and got 10,000.
for b) I divided $100x10^9$ by $10,000$ and got 10,000,000.

2. Originally Posted by viet
can someone check if the answer is right?

for a) I divided $100x10^9$ by $10^7$ and got 10,000.
for b) I divided $100x10^9$ by $10,000$ and got 10,000,000.
Part A is fine.

For part B you should multiply by $10^4$ because you've established that there are $10^4$ Earth-like planets in each galaxy.