If x and y are two-digit integers such that x > 40

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Gmat_mission: Legendary Member; Posts: 1622; Joined: Thu Mar 01, 2018 7:22 am; Followed by:2 members

If x and y are two-digit integers such that x > 40

by Gmat_mission » Sun Mar 11, 2018 8:44 am

If x and y are two-digit integers such that x > 40 and y<70, which of the following is closest to the maximum possible value of xy ?

(A) 700
(B) 2,800
(C) 4,000
(D) 7,000
(E) 28,000

[spoiler]OA=D[/spoiler].

How can I determine the correct answer here? If I don't know the value of x and y, how can I find a value of xy?

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Source: Beat The GMAT — Problem Solving | Sun Mar 11, 2018 8:44 am

GMATGuruNY: GMAT Instructor; Posts: 15539; Joined: Tue May 25, 2010 12:04 pm; Location: New York, NY; Thanked: 13060 times; Followed by:1906 members; GMAT Score:790

by GMATGuruNY » Sun Mar 11, 2018 10:09 am

Gmat_mission wrote:If x and y are two-digit integers such that x > 40 and y<70, which of the following is closest to the maximum possible value of xy ?

(A) 700
(B) 2,800
(C) 4,000
(D) 7,000
(E) 28,000

Since x and y are two-digit integers such that x>40 and y<70:
40 < x â‰¤ 99.
10 â‰¤ y < 70.

Thus:
Maximum possible value for x = 99.
Maximum possible value for y = 69.
Maximum possible value for xy = 99*69 = (100-1)(70-1) â‰ˆ 100*70 = 7000.

The correct answer is D.

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by Scott@TargetTestPrep » Sun Jun 09, 2019 5:58 pm

Gmat_mission wrote:If x and y are two-digit integers such that x > 40 and y<70, which of the following is closest to the maximum possible value of xy ?

(A) 700
(B) 2,800
(C) 4,000
(D) 7,000
(E) 28,000

The maximum value of xy is 99 * 69, which is approximately 100 * 70 = 7,000.

Answer: D

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