If it takes Annette 13 minutes to jog a yards and she continues at tha

Question

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)

GMATinsight · Answer

CONCEPT :  \frac{(Machine_Power * Time)}{Work} = Constant   
i.e.  \frac{(M_1 * T_1)}{W_1} = \frac{(M_2 * T_2)}{W_2}

i.e.  \frac{(A * 13)}{a} = \frac{(A * T_2)}{b}

i.e.  T_2 = 13b/a

Answer: option D

Abhishek009 · Answer

Annette can jog a yards in 13 min
So, Annette can jog 1 yard in 13/a min
And, She can jog b yards in 13b/a min

Answer will be (D)

bobbyhadr · Answer

i got C for my answer

13 minutes to finish  a  yards which will be translated to  3a feet 
which mean = (3a)/13 (ft/min)
in order to get the time she took to complete b feet will be

B / {(3a/13)} = 13b/(3A)

so i choose C, so which part is wrong?

pushpitkc · Answer

Can you please explain how you got the highlighted part?

chetan2u · Answer

Hi..

It is not that you have gone wrong, all others have gone wrong by not differentiating between yards and feet... 
13 min to travel a yard...so 13 min for 3a feet..
1 feet in  \frac{13}{3a}  and b feet in  \frac{13b}{3a}

C

pushpitkc · Answer

Shouldn't that information be updated in the question stem(or are we supposed to know the basic conversions)?

chetan2u · Answer

The info on conversion rate would normally be given.... OR the question would stick to only yards in official questions

bobbyhadr · Answer

the question asked how long does it take to complete b   feet  
not in a yard

kapil123 · Answer

He is asking how much time it will take to cover b feet not b yard. 
So C is our winner.

Sent from my iPhone using GMAT Club Forum

Bunuel · Answer

Edited the stem.

Check other  Conversion problems  to practice in  Special Questions Directory .

JeffTargetTestPrep · Answer

Annette’s rate is a/13 yards per minute and b feet = b/3 yards, so it will take her b/3/(a/13) = 13b/(3a) minutes to jog b feet.

Answer: C

kshitij89 · Answer

Hi Abhishek,

The question is asking about the time to cover 'b feet' whereas you have calculated the time for 'b yard'. So this is wrong.

The solution is as below :

13 min to cover a yard = 3a feet
So , speed = 3a/13 feet/min

Now, to cover b feet , time will be b*13/3a = 13b/3a

So C should be correct.

Regards
Kshitij

AkshdeepS · Answer

Given Distance 1 = a yards or 3a feet

Time 1 = 13 minutes

Speed 1 = D1/T1 = 3a/13

D2 = b feet

S2 = S1 = 3a/13

Time 2 = D2/S2

= \frac{(b)}{(3a/13)}

= \frac{13b}{3a}

hence (C)

generis · Answer

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}
eq{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
eq{13}  NO

ANSWER C

bumpbot · Answer

Automated notice from GMAT Club BumpBot: 

A member just gave Kudos to this thread, showing it’s still useful. I’ve bumped it to the top so more people can benefit. Feel free to add your own questions or solutions.

 This post was generated automatically.

If it takes Annette 13 minutes to jog a yards and she continues at tha

Prep Toolkit

Top 5 GMAT Debrief Videos

615 to 715 in 15 Days (Ria's Strategies)

More than Quant/Verbal Abilities: Speed vs. Accuracy

745 with Only Self-Prep and GMAT Club

From 555 to 765: 210-point Improvement

Perfect 805 Score Debrief by Julia

My Rewards

GMAT Problem Solving (PS) Questions

If it takes Annette 13 minutes to jog a yards and she continues at tha

Prep Toolkit

615 to 715 in 15 Days (Ria's Strategies)

More than Quant/Verbal Abilities: Speed vs. Accuracy

745 with Only Self-Prep and GMAT Club

From 555 to 765: 210-point Improvement

Perfect 805 Score Debrief by Julia

My Rewards