a varies directly as b and inversely as the square of c. If a=65 when b=9 and c=7, find a if b=3 and c=8. Round your answer to two decimal places if necessary.

Answer 1

a = kb/c^2

65= k9/49

9k = 65(49) = 3185

k = 3185/9 = 353 8/9

a = 3185b/9c^2

a= 3185(3)/9(8^2) = (3185)/27)(64) = 3185/1728 = about 1.84

a= about 1.84 when b= 3 and c = 8