Can someone please help me with the following question.

Question

1) The weight of an object above Earth can be modeled by a function of the form w(h)=(r/r+h)^2*"w , where r is the radius of Earth
0"
(approximately 3950 miles)," h" is the distance above Earth's surface, and
"w is the weight of the object on the surface of the Earth.
0"

a) At what height will a 150-pound object weigh 50 pounds?
I used the following:"w = 150 w(h)= 50 r=3950
0"
So I plugged these values into the equation given:
50=(3950/3950 + h)^2*150
and my answer was h= 7900
b) How high would a crow carrying a whelk haveto fly for the whelk's weight to change by 0.1%?

Answer 1

Don't know how you got 7900.

50=(3950/3950 + h)^2*150
transpose and square root
(3950+h)/3950 = sqrt(150/50)
h=6842-3950=2892 (miles)

Similarly for the crow:
(3950+h)/3950)=sqrt(1.001/1.000)
h=1.97 miles