Today, Barry Reached His 50^th Birthday and He Has $70,000

Today, Barry reached his 50^th birthday and he has $70,000 in his retirement fund. His goal is to have $500,000 on his 65^th birthday. He can expect his investments to earn 13% compounded semi-annually. How much will he have to invest at the end of every six months for the next 15 years in order to reach his goal?

A) $4,978.30
B) $1,722.84
C) $428.30
D) $926.14
E) $2,388.89