424 McGRAW-HILL’S SAT
SAT Practice 4: Variation
- If pvaries inversely as qand p= 4 when q= 6,
then which of the following represents another
possible solution for p and q?
(A) p= 8 and q= 12
(B) p= 8 and q= 10
(C) p= 10 and q= 12
(D) p= 12 and q= 1
(E) p= 12 and q= 2 - Which of the following describes one possible
relationship between the values of m and n
shown in the table above?
(A) nvaries directly as m
(B) nvaries inversely as m
(C) nvaries directly as the square of m
(D) nvaries inversely as the square of m
(E) nvaries directly as the square root of m - If the function fis defined by the equation
f(x, y) = x^2 y^3 and f(a, b) = 10, what is the value
of f(2a, 2b)?
(A) 50
(B) 100
(C) 160
(D) 320
(E) 640 - At a fixed temperature, the volume of a sample
of gas varies inversely as the pressure of the
gas. If the pressure of a sample of gas at a fixed
temperature is increased by 50%, by what per-
cent is the volume decreased?
(A) 25%
(B) %
(C) 50%
(D) 75%
(E) 100%
(^3313)
- The force of gravity between two stars varies in-
versely as the square of the distance between
the stars. If the force of gravity between two
stars that are four light-years apart is 64 ex-
anewtons (1 exanewton = 10^18 newtons), what
would the force between these stars be if they
were eight light-years apart?
(A) 256 exanewtons
(B) 128 exanewtons
(C) 32 exanewtons
(D) 16 exanewtons
(E) 8 exanewtons - If the variable a varies directly as b and in-
versely as c, and if a= 10x+ 5 when c= 2 and
b= 10, then what is the value of awhen b= 4
and c= 2x+ 1?
....1 2 3 4 5 7 8 9610 2 3 4 5 7 8 9610 2 3 4 5 7 8 9610 2 3 4 5 7 8 96