Two identical but separate strings, with the same tension, carry sinusoidal waves with the same frequency. Wave A has an amplitude that is twice that of wave B and transmits energy at a rate that is _____ that of wave B.

a)half
b)twice
c) one-fourth
d)four times
e) eight times

work:
I thought the answer was twice or b because a higher energy wave is characterized by a higher amplitude while a lower energy wave is characterized by a low amplitude.

A sinusoidal water waves are generated in a large ripple tank. The waves travel at 20cm/s and their adjacent crests are 5.0cm apart. The time required for each new whole cycle to be generated is.
a)100s
b)4.0s
c)2.0s
d)0.5s
e)0.25s

answer:
v=lambda *f
20 cm/s= (5.0cm)*f
f=4
T=1/4
T=.25s

Please check my answers and help point me in the right direction.
Thank you