Question:
If 4 men working at the same rate can do 2/3 of a job in 40 minutes, how many minutes would it take 1 man working at this rate to do 2/5 of the job?
Answers:
80, 88, 92, 96, 112
How would you tackle this problem?
Below is how I solved it, but I feel like there is an easier way to do this problem. Any suggestions? How would you rate this problems difficulty?
WARNING: SPOILER BELOW:
2/3 Job / 4 Men = (2/3)/4 = 1/6... therefore each man does 1/6 of the job in 40 minutes.
1/6 Job / 40 minutes = (1/6)/40 = 1/240... therefore each man does 1/240 of the job per minute
Using Distance (Work) = Rate * Time
2/5 = 1/240 * time
2/5 * 240 = time
48 * 2 = 96
Work/Rate Problem
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- franciskyle
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another approach by unitary method
no of men is inversely proportional to the time taken
if 4 men do 2/3 W in 40 mins
1 man does 2/3 W in 40*4=160 mins
1 man 2/3W in 160 mins
1 man 2/5W in 160*3/2*2/5=96 mins
no of men is inversely proportional to the time taken
if 4 men do 2/3 W in 40 mins
1 man does 2/3 W in 40*4=160 mins
1 man 2/3W in 160 mins
1 man 2/5W in 160*3/2*2/5=96 mins
(4 man x 40 min )160 man-minute = 2/3X, where X is number of man-minutes originally required. X=240 man-minutes. 2/5 of 240 man minutes. 96man min. 1 man x 96 mins = 96 man mins. Leave all that 1/6 job analysis begin (laugh).franciskyle wrote:Question:
If 4 men working at the same rate can do 2/3 of a job in 40 minutes, how many minutes would it take 1 man working at this rate to do 2/5 of the job?
Answers:
80, 88, 92, 96, 112
How would you tackle this problem?
Below is how I solved it, but I feel like there is an easier way to do this problem. Any suggestions? How would you rate this problems difficulty?
WARNING: SPOILER BELOW:
2/3 Job / 4 Men = (2/3)/4 = 1/6... therefore each man does 1/6 of the job in 40 minutes.
1/6 Job / 40 minutes = (1/6)/40 = 1/240... therefore each man does 1/240 of the job per minute
Using Distance (Work) = Rate * Time
2/5 = 1/240 * time
2/5 * 240 = time
48 * 2 = 96