College Algebra

Question

Suppose that y varies directly as the square root of x, and that y=21 when x=361. What is y when x=247? (Round off your answer to 2 decimal places)

Answer 1

We can set this up as a proportion.

21/361 = y/247

21y = 361(247)

21y = 89,167

y = 4246.05

With indirect variation, you would flip one of the ratios, cross multiply, and solve in the same manner.

Answer 2

Suppose that y varies directly as the square root of x

y/√x = k

 y=21 when x=361

21/√361 = 1.10526315789

y/√247 = 1.10526315789

y = 17.3705740292 = 17.37