Verified answer

ans1) The equation for the observed frequency of sound when the source is traveling toward you is:

fo = fv/(v − vt)

where

fo is the observed frequency

f is the emitted frequency

v is the velocity of sound

vt is the velocity of the source toward you

v > vt (vt is less than v)

Note that this equation does not work if the speed of the source is equal to the speed of sound. In such as case, you would be dividing by 0, which is impossible.

ATQ

756*340/(340-21.5) =756*340/318.5= 807.03Hz(approx.)