Ann takes 50 percent more time to complete a job working alone than

Question

Ann takes 50 percent more time to complete a job working alone than Ann and Bob take to complete the job when working together. By what percent does Bob take more time to complete the job working alone than Ann and Bob take to complete the job when working together?

A. 50%
B. 75%
C. 100%
D. 150%
E. 200%

A. 50%
B. 75%
C. 100%
D. 150%
E. 200%

M47-02

Bunuel · Accepted Answer

GMAT Club Official Solution:

Let the time for Ann and Bob working together be 2 hours.

Then Ann alone would take 3 hours.

In 2 hours, Ann would complete 2/3 of the job, so Bob would complete the remaining 1/3 in those same 2 hours. Therefore, to complete the entire job alone, Bob would need 2 * 3 = 6 hours. So, Bob takes 6/2 = 3 times as long to complete the job as Ann and Bob take together, which means Bob takes 200% more time.

Answer: E.

sujoykrdatta · Answer

Ann takes 50 percent more time to complete a job working alone than Ann and Bob take to complete the job when working together

=> Ann takes 3/2 times the time to complete a job working alone than Ann and Bob take to complete the job when working together

=> Efficiency of Ann is 2/3 of the efficiency of Ann+Bob

=> If efficiency (rate) of A+B is 3, efficiency of A is 2 and hence that of B is 1

=> Bob is 1/3 rd as efficient as A+B

=> Bob takes thrice the time as that taken by A+B

=> Required percent = 200% more

Answer E

GMATFE2025 · Answer

Lets assume Ann (A) and Bob (B) takes 100 days to complete the job, Hence Rate (A+B) = 1/100
As per question stem Ann (A) takes alone 50% more of 100 = 150 days or Rate (A) = 1/150
Rate (B) = Rate (A+B) - Rate (A) = 1/100 - 1/150 = 1/300

So B takes 300 days to complete the job that A+B completes in 100 days.

Question asked by what % does B takes more than (A+B) = (300-100)/100 = 200%

Amity007 · Answer

A takes 50% that is 1/2 more so time taken will be 3/2 and rate will be 2/3.
Now we can calculate rate of B = 1-2/3 =1/3
So time taken by b is 3/1
Now calculate the percentage extra time taken, (3-1 / 1) *100 =200 option E.
“For percent calculation we are taking extra   *100”

Dereno · Answer

Ann takes 50% more time than Ann and Bob combined.

A = (3/2) (A+B)

The time ratio of A : (A+B) = 3:2

Efficiency ratio of A : (A+B) = 2:3. Then , we can say B efficiency =1.

Total work = 3*2 = 6 units.

Time taken by Ann is (6/2) = 3

Time taken by Bob = (6/1) = 6

Time taken by Ann and Bob = (6/3)= 2

By what percent does Bob take more time to complete the job working alone than Ann and Bob take to complete the job when working together?

Bob takes 4 hrs more than both Ann and Bob combined.

% = (4/2) *100 =  200%.

Option E

thuckhang · Answer

A takes 50% more time than A+B 
rate A 1.5/a = 1/a + 1/b => a/b = 1/2 => 2a=b 
Question asks: 1/b = x (1/a + 1/b), 2a =b 
=> 1/b = x (1/(b/2) + 1/b) => x = 3 
% more: (new - original)/orginal*100 = 3-1/1 *100 = 200%

Ann takes 50 percent more time to complete a job working alone than

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