What frequency does the blood receive? What frequency return

[CMATT]

Homework Statement

Ultrasound reflected from an oncoming bloodstream that is moving at 28.7 cm/s is mixed with the original frequency of 2.41 MHz to produce beats. Use the speed of sound in human tissue as 1540 m/s. Assume that the frequency of 2.41 MHz is accurate to seven significant figures. (Hint: compare to Example 17.8 in OpenStaxCollege Physics.)

a) What frequency does the blood receive? (Give an answer in MHz, to 7 significant figures.)

b) What frequency returns to the source? (Give an answer in MHz, to 7 significant figures.)

c) What beat frequency is produced if the source and returning frequencies are mixed? (Give an answer in Hz, to 3 significant figures.)

Homework Equations

f_(observed) = f_(s) x (V_w / V_w +/- V_s)

f_(observed) = f_(s) x (V_w +/- V_(obs)) / V_w

The Attempt at a Solution

a)
(2,410,000 Hz)(1540 m/s + .287 m/s) / 1540 m/s) = 2410449.136 Hz = 2.410449 MHz

b)
(2410449 Hz)(1540 / 1540 - .287) = 2410948.313 Hz = 2.410948 MHz

c) 2410948.313 - 2410000 = 948 Hza) is correct, I got that one right. b) and c) are wrong. I thought I did them correctly. Could someone please help?
Thank you!

 

[CMATT]

NEVERMIND! I solved it