If k and m are numbers such that k + m = 20 and k^2 + m^2 = 289, then the value of the product km is
(A) between 20 and 60
(B) between 60 and 100
(C) between 100 and 150
(D) between 150 and 200
(E) greater than 200
Answer: A
Source: GMAT prep
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If k and m are numbers such that k + m = 20 and k^2 + m^2 = 289, then the value of the product km is
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BTGModeratorVI
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If k and m are numbers such that k + m = 20 and k^2 + m^2 = 289, then the value of the product km is
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GIVEN: k + m = 20 and k² + m² = 289BTGModeratorVI wrote: ↑Sat Aug 08, 2020 7:07 amIf k and m are numbers such that k + m = 20 and k^2 + m^2 = 289, then the value of the product km is
(A) between 20 and 60
(B) between 60 and 100
(C) between 100 and 150
(D) between 150 and 200
(E) greater than 200
Answer: A
Source: GMAT prep
Take: k + m = 20
Square both sides to get: (k + m)² = 20²
Expand and simplify the left side: k² + 2km + m² = 400
Rewrite as: (k² + m²) + 2km= 400
Substitute to get: (289) + 2km= 400
Subtract 289 from both sides to get: 2km = 111
Divide both sides by 2 to get: km = 55.5
Answer: A
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Solution:BTGModeratorVI wrote: ↑Sat Aug 08, 2020 7:07 amIf k and m are numbers such that k + m = 20 and k^2 + m^2 = 289, then the value of the product km is
(A) between 20 and 60
(B) between 60 and 100
(C) between 100 and 150
(D) between 150 and 200
(E) greater than 200
Answer: A
Source: GMAT prep
Since k + m = 20, we have:
(k + m)^2 = 20^2
k^2 + m^2 + 2km = 400
Since k^2 + m^2 = 289, we have:
289 + 2km = 400
2km = 111
km = 55.5
Answer: A
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