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Eighty percent of the lights at Hotel California are on at 8 p.m.
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31 Mar 2021, 09:24
31 Mar 2021, 09:24
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Eighty percent of the lights at Hotel California are on at 8 p.m. a certain evening. However, forty percent of the lights that are supposed to be off are actually on and ten percent of the lights that are supposed to be on are actually off. What percent of the lights that are on are supposed to be off?
A. 22(2/9)%
B. 16(2/3)%
C. 11(1/9)%
D. 10%
E. 5%
A. 22(2/9)%
B. 16(2/3)%
C. 11(1/9)%
D. 10%
E. 5%
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Re: Eighty percent of the lights at Hotel California are on at 8 p.m.
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31 Mar 2021, 10:35
31 Mar 2021, 10:35
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GeminiHeat wrote:
Eighty percent of the lights at Hotel California are on at 8 p.m. a certain evening. However, forty percent of the lights that are supposed to be off are actually on and ten percent of the lights that are supposed to be on are actually off. What percent of the lights that are on are supposed to be off?
A. 22(2/9)%
B. 16(2/3)%
C. 11(1/9)%
D. 10%
E. 5%
A. 22(2/9)%
B. 16(2/3)%
C. 11(1/9)%
D. 10%
E. 5%
You can use Double matrix to solve fast!
Let the total lights be \(100\)
On = \(80\)
Off = \(20\)
\(40\)% of the lights that are supposed to be off are actually on = \(\frac{40}{100}(20) = 8\)
\(10\)% of the lights that are supposed to be on are actually off = \(\frac{10}{100}(80) = 8\)
So, % of lights that are on and are supposed to be off = \(\frac{8}{80}(100) = 10\)%
Hence, option D
Re: Eighty percent of the lights at Hotel California are on at 8 p.m.
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01 Apr 2021, 11:45
01 Apr 2021, 11:45
KarunMendiratta wrote:
GeminiHeat wrote:
Eighty percent of the lights at Hotel California are on at 8 p.m. a certain evening. However, forty percent of the lights that are supposed to be off are actually on and ten percent of the lights that are supposed to be on are actually off. What percent of the lights that are on are supposed to be off?
A. 22(2/9)%
B. 16(2/3)%
C. 11(1/9)%
D. 10%
E. 5%
A. 22(2/9)%
B. 16(2/3)%
C. 11(1/9)%
D. 10%
E. 5%
You can use Double matrix to solve fast!
Let the total lights be \(100\)
On = \(80\)
Off = \(20\)
\(40\)% of the lights that are supposed to be off are actually on = \(\frac{40}{100}(20) = 8\)
\(10\)% of the lights that are supposed to be on are actually off = \(\frac{10}{100}(80) = 8\)
So, % of lights that are on and are supposed to be off = \(\frac{8}{80}(100) = 10\)%
Hence, option D
I have been trying with double matrix, but can't do it right way. Will you please help?
