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When a certain stretch of highway was rebuilt and straighten
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05 Feb 2020, 07:35
05 Feb 2020, 07:35
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When a certain stretch of highway was rebuilt and straightened, the distance along the stretch was decreased by 20 percent and the speed limit was increased by 25 percent. By what percent was the driving time along this stretch reduced for a person who always drives at the speed limit?
(A) 16%
(B) 36%
(C) 37.5 %
(D) 45%
(E) 56.25 %
(A) 16%
(B) 36%
(C) 37.5 %
(D) 45%
(E) 56.25 %
Re: When a certain stretch of highway was rebuilt and straighten
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05 Feb 2020, 23:45
05 Feb 2020, 23:45
Asif123 wrote:
When a certain stretch of highway was rebuilt and straightened, the distance along the stretch was decreased by 20 percent and the speed limit was increased by 25 percent. By what percent was the driving time along this stretch reduced for a person who always drives at the speed limit?
(A) 16% (B) 36% (C) 37.5 % (D) 45% (E) 56.25 %
(A) 16% (B) 36% (C) 37.5 % (D) 45% (E) 56.25 %
Base case formula is:
T*R = D
After reconstruction, we have:
T*R*1.25 = 0.8D (R is increased by 25%; D is reduced by 20%)
Previous T = D/R
Post-reconstruction T is 0.8D/1.25R = 0.64 (D/R)
That means that the driving time is reduced by 1- 0.64 = 36%.
Re: When a certain stretch of highway was rebuilt and straighten
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14 Dec 2021, 00:58
14 Dec 2021, 00:58
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