Bunuel wrote:

If it takes Annette 13 minutes to jog a yards and she continues at that rate for b feet, how long will it take Annette to complete the b feet? (1 yard = 3 feet)

A. 13a/(3b)

B. 39b/a

C. 13b/(3a)

D. 13b/a

E. b/(39a)

Another approach: assign values.

Annette takes 13 minutes to jog \(a = 2\) yards.

Rate:

\(\frac{2yds}{13mins}\)Rate in feet (multiply yards by 3):

\(\frac{2yds}{13mins}=\frac{(2*3)}{13mins}=\frac{6ft}{13mins}\)Let \(b\) feet = \(6\)

If she runs 6 feet in 13 minutes . . . to run 6 feet will take 13 minutes.

(\(b\), in other words is distance.) D/r = time

\(t=\frac{D}{r}=\frac{6ft}{(\frac{6ft}{13mins})}=(6ft*\frac{13mins}{6ft})=13\) mins

Answer choices: use \(a = 2\), \(b = 6\). We need the option that yields answer \(13\)

Eliminate B and E immediately

--B's numerator is too great without \(b\) (hence even greater when multiplied * 6).

--E's denominator is too great without \(a\)

A. 13a/(3b): \(\frac{13*2}{(3*6)}=\frac{26}{18}\neq{13}\) NO

C. 13b/(3a): \(\frac{13*6}{(3*2)}=\frac{78}{6}=13\) MATCH

D. 13b/a: \(\frac{(13*6)}{2}=\frac{78}{2}=39\neq{13}\) NO

ANSWER C