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Working at their normal constant rates, 20 diggers can dig a 100meter
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Updated on: 27 Dec 2018, 21:37
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Working at their normal constant rates, 20 diggers can dig a 100meter long trench in hard soil in 3 days. A construction company ordered the diggers to dig a 180meter long trench in soft soil. If diggers can work 20% faster in soft soil than in hard soil, how many diggers are required to complete this task in 3 days? A. 25 B. 28 C. 29 D. 30 E. 32
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Originally posted by ritu1009 on 27 Dec 2018, 00:30.
Last edited by ritu1009 on 27 Dec 2018, 21:37, edited 2 times in total.



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Re: Working at their normal constant rates, 20 diggers can dig a 100meter
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27 Dec 2018, 00:40
ritu1009 wrote: Working at their normal constant rates, 20 diggers can dig a 100meter long trench in hard soil in 3 days. A construction company ordered the diggers to dig a 180meter long trench in soft soil. If diggers can work 20% faster in soft soil than in hard soil, how many diggers are required to complete this task in 3 days?
A.25 B.28 c.29 D. 30 E. 32 20 diggers can dig a 100meter long trench in hard soil in 3 days. In 1 day, 1 digger can dig 100/20/3 = 5/3 meter with increased efficiency, In 1 day, 1 digger can dig 5/3*1.2 = 2 meter No. of diggers required to dig 180 meter in 3 days with increased efficiency = 180/3/2 = 30 Answer D
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Re: Working at their normal constant rates, 20 diggers can dig a 100meter
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27 Dec 2018, 01:19
ritu1009 wrote: Working at their normal constant rates, 20 diggers can dig a 100meter long trench in hard soil in 3 days. A construction company ordered the diggers to dig a 180meter long trench in soft soil. If diggers can work 20% faster in soft soil than in hard soil, how many diggers are required to complete this task in 3 days?
A. 25 B. 28 C. 29 D. 30 E. 32 20 diggers can dig a 100meter long trench in hard soil in 3 days; 1 digger can dig a 100/20=5meter long trench in hard soil in 3 days; 1 digger can dig a 5*1.2=6meter long trench in soft soil in 3 days; Therefore, to dig 180meter long trench in soft soil in 3 days \(\frac{180}{6}=30\) diggers are required. Answer: D P.S. You must provide the OA when posting a question.
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Re: Working at their normal constant rates, 20 diggers can dig a 100meter
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28 Dec 2018, 01:33
ritu1009 wrote: Working at their normal constant rates, 20 diggers can dig a 100meter long trench in hard soil in 3 days. A construction company ordered the diggers to dig a 180meter long trench in soft soil. If diggers can work 20% faster in soft soil than in hard soil, how many diggers are required to complete this task in 3 days?
A. 25 B. 28 C. 29 D. 30 E. 32 time for 1 digger to dig : 60 days so rate would be 100/60 = 5/3 soft soil rate = 5/3 * 1.2 = 2 mtrs per day in 3 days they can dig 2*3= 6 mtrs so for 180 mtrs = 180/6= 30 diggers required IMO D
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Re: Working at their normal constant rates, 20 diggers can dig a 100meter
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28 Dec 2018, 13:18
ritu1009 wrote: Working at their normal constant rates, 20 diggers can dig a 100meter long trench in hard soil in 3 days. A construction company ordered the diggers to dig a 180meter long trench in soft soil. If diggers can work 20% faster in soft soil than in hard soil, how many diggers are required to complete this task in 3 days?
A. 25 B. 28 C. 29 D. 30 E. 32 Dear GMATinsightCan you help please with this question? I tried to use the same concept you did below but failed: https://gmatclub.com/forum/acompanys ... ght%20fuelThanks in advance



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Working at their normal constant rates, 20 diggers can dig a 100meter
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28 Dec 2018, 23:48
Mo2men wrote: ritu1009 wrote: Working at their normal constant rates, 20 diggers can dig a 100meter long trench in hard soil in 3 days. A construction company ordered the diggers to dig a 180meter long trench in soft soil. If diggers can work 20% faster in soft soil than in hard soil, how many diggers are required to complete this task in 3 days?
A. 25 B. 28 C. 29 D. 30 E. 32 Dear GMATinsightCan you help please with this question? I tried to use the same concept you did below but failed: https://gmatclub.com/forum/acompanys ... ght%20fuelThanks in advance Mo2menPlease find below my explanation in the similar way 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. \(\frac{(20 * 3)}{100} = \frac{(M_2 *1.2 * 3)}{180}\) i.e. \(M_2 = 20*(180/100)/1.2\) i.e. \(M_2 = 30\) I hope this helps!!!
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Re: Working at their normal constant rates, 20 diggers can dig a 100meter
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29 Dec 2018, 06:10
GMATinsight wrote: Mo2men wrote: ritu1009 wrote: Working at their normal constant rates, 20 diggers can dig a 100meter long trench in hard soil in 3 days. A construction company ordered the diggers to dig a 180meter long trench in soft soil. If diggers can work 20% faster in soft soil than in hard soil, how many diggers are required to complete this task in 3 days?
A. 25 B. 28 C. 29 D. 30 E. 32 Dear GMATinsightCan you help please with this question? I tried to use the same concept you did below but failed: https://gmatclub.com/forum/acompanys ... ght%20fuelThanks in advance Mo2menPlease find below my explanation in the similar way 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. \(\frac{(20 * 3)}{100} = \frac{(M_2 *1.2 * 3)}{180}\) i.e. \(M_2 = 20*(180/100)/1.2\) i.e. \(M_2 = 30\) I hope this helps!!! Thanks GMATinsight for your response and explanation.



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Working at their normal constant rates, 20 diggers can dig a 100meter
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01 Jan 2019, 21:04
Solution Given:• 20 diggers can dig a 100 m long trench, in hard soil, in 3 days • Now, they must dig a 180 m long trench in soft soil • They can work 20% faster in soft soil than in hard soil To find:• The number of diggers required to complete the task in 3 days Approach and Working: In Hard Soil:• 20 diggers can dig \(\frac{100}{3}\) m in 1 day • 1 person can dig \(\frac{100}{(3 * 20)} = \frac{5}{3}\) m in 1 day In Soft Soil:• 1 person can dig \((\frac{5}{3} * 1.2) = 2\) m in 1 day • Thus, 1 person can dig (2 * 3) m = 6 m in 3 days Therefore, we need \(\frac{180}{6} = 30\) diggers to dig 180 m in 3 days Hence, the correct answer is Option D Answer: D
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Working at their normal constant rates, 20 diggers can dig a 100meter
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