How many nanoseconds are there in 1.00 yr ? (it needs to be shown using only 3 significant figures. i came up with 1.89 x 10^9. however it doesn't seem figured it made a simple calculation error. the answer is 3.16x10^16

Two loudspeakers, 5.5 m apart and facing each other, play identical sounds of the same frequency. you stand halfway between them, where there is a maximum of sound intensity. moving from this point toward one of the speakers, you encounter a minimum of sound intensity when you have moved 0.33 m . assume the speed of sound is 340 m/s.part a) what is the frequency of the sound? part b) if the frequency is then increased while you remain 0.21 m from the center, what is the first frequency for which that location will be a maximum of sound intensity? express your answer to two significant figures and include the appropriate units.