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# If the average (arithmetic mean) of p, q and r is 50 and the average

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Math Expert
Joined: 02 Sep 2009
Posts: 43348

Kudos [?]: 139709 [0], given: 12794

If the average (arithmetic mean) of p, q and r is 50 and the average [#permalink]

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28 Dec 2017, 20:53
00:00

Difficulty:

25% (medium)

Question Stats:

85% (00:41) correct 15% (01:02) wrong based on 27 sessions

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If the average (arithmetic mean) of p, q and r is 50 and the average ( arithmetic mean) of q, r and s is 60, what is the value of s – p?

A. 60
B. 50
C. 40
D. 30
E. 10
[Reveal] Spoiler: OA

_________________

Kudos [?]: 139709 [0], given: 12794

Manager
Joined: 24 Nov 2016
Posts: 151

Kudos [?]: 32 [0], given: 40

Re: If the average (arithmetic mean) of p, q and r is 50 and the average [#permalink]

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29 Dec 2017, 03:10
Bunuel wrote:
If the average (arithmetic mean) of p, q and r is 50 and the average ( arithmetic mean) of q, r and s is 60, what is the value of s – p?

A. 60
B. 50
C. 40
D. 30
E. 10

$$Average=\frac{Sum}{Terms}$$

$$\frac{(q+r+s)}{3}=60$$, $$q+r+s=180$$

$$\frac{(p+q+r)}{3}=50$$, $$p+q+r=150$$

$$(q+r+s)-(p+q+r)=180-150$$, $$s-p=30$$.

Kudos [?]: 32 [0], given: 40

Intern
Joined: 28 Dec 2017
Posts: 24

Kudos [?]: 1 [0], given: 0

Re: If the average (arithmetic mean) of p, q and r is 50 and the average [#permalink]

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20 Jan 2018, 22:08
(p + q + r)/3 = 50
Hence, p + q + r = 150 Equation 1

(q + r + s)/3 = 60
Hence, q + r + s = 180 Equation 2

Subtract Equation 1 from Equation 2:
(q + r + s) - (p + q + r) = 180 - 150
s - r = 30 (Answer D)

Kudos [?]: 1 [0], given: 0

Re: If the average (arithmetic mean) of p, q and r is 50 and the average   [#permalink] 20 Jan 2018, 22:08
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