SAT Mathematics Practice Test 7

If Mosteller’s and Current’s formulas give the same estimate for A, then the right-hand sides of these two equations are equal; that is

√hw

60

=

4+w

30

. Multiplying each side of this equation by 60 to isolate the expression √hw gives √hw=60(

4+w

30

) or √hw=2(4+w). Therefore, if Mosteller’s and Current’s formulas give the same estimate for A, then √hw is equivalent to 2(4 + w).An alternate approach is to multiply the numerator and denominator of Current’s formula by 2, which gives

2(4+w)

60

. Since it is given that Mosteller’s and Current’s formulas give the same estimate for A,

2(4+w)

60

=

√hw

60

. Therefore, √hw=2(4+w)