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Bunuel
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In Cliff’s impressive rock collection, there are half as many igneous 29 Feb 2016, 10:35
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In Cliff’s impressive rock collection, there are half as many igneous rocks as sedimentary rocks. Of the igneous rocks, 2/3 are shiny and the rest are matte, while 1/5 of the sedimentary rocks are shiny. If there are 30 shiny igneous rocks, how many total rocks does Cliff have?

A. 30
B. 45
C. 60
D. 90
E. 135
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E
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In Cliff’s impressive rock collection, there are half as many igneous 01 Mar 2016, 22:26
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Bunuel
In Cliff’s impressive rock collection, there are half as many igneous rocks as sedimentary rocks. Of the igneous rocks, 2/3 are shiny and the rest are matte, while 1/5 of the sedimentary rocks are shiny. If there are 30 shiny igneous rocks, how many total rocks does Cliff have?

A. 30
B. 45
C. 60
D. 90
E. 135
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Assume total sedimentary rocks to be 2x
Total igneous rocks = x

Shiny igneous rocks = 2x/3
Matte igneous rocks = x/3

Shiny sedimentary rocks = 2x/5

Given 2x/3 = 30
x = 45

Total rocks = igneous + sedimentary = x + 2x = 3*45 = 135
Option E
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In Cliff’s impressive rock collection, there are half as many igneous 01 Mar 2016, 23:56
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Bunuel
In Cliff’s impressive rock collection, there are half as many igneous rocks as sedimentary rocks. Of the igneous rocks, 2/3 are shiny and the rest are matte, while 1/5 of the sedimentary rocks are shiny. If there are 30 shiny igneous rocks, how many total rocks does Cliff have?

A. 30
B. 45
C. 60
D. 90
E. 135
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We can start with the known quantity and then go on to find the others.

Shiny igneous ricks are 30. These are (2/3) of total igneous rocks.
(2/3)*Total igneous rocks = 30
Total igneous rocks = 30 * (3/2) = 45

Total sedimentary rocks = 2*Total igneous rocks = 2*45 = 90

Total number of rocks = 45 + 90 = 135

Answer (E)
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In Cliff’s impressive rock collection, there are half as many igneous 10 May 2017, 20:02
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Let sedimentary rocks = x
So igneous rocks = x/2

Shiny igneous = x/2 * 2/3 = x/3
We are given that shiny igneous rocks are 30
So x/3 = 30; thus x=90
Implying that sedimentary rocks are 90, igneous rocks are 90/2 =45.
So total = 135

option E
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In Cliff’s impressive rock collection, there are half as many igneous 15 May 2017, 17:33
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Bunuel
In Cliff’s impressive rock collection, there are half as many igneous rocks as sedimentary rocks. Of the igneous rocks, 2/3 are shiny and the rest are matte, while 1/5 of the sedimentary rocks are shiny. If there are 30 shiny igneous rocks, how many total rocks does Cliff have?

A. 30
B. 45
C. 60
D. 90
E. 135
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We can let the number of igneous rocks = x.

Since 2/3 of the igneous rocks are shiny and since we know that there are 30 shiny igneous rocks, we have:

(2/3)x = 30

2x = 90

x = 45

Since Cliff has half as many igneous rocks as he has sedimentary rocks, he has 90 sedimentary rocks. Thus, in total there are 45 + 90 = 135 rocks.

(Note that the information that 1/5 of the sedimentary rocks were shiny is not necessary for the solution.)

Answer: E
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In Cliff’s impressive rock collection, there are half as many igneous 21 Jan 2021, 19:47
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Let g be igneous rocks
Let s be sedimentary

g = s/2 Igneous rocks
s = g x 2 Sedimentary rocks

2/3g = 30 ---> g = 45 igneous rocks

45 = s/2 ---> s = 90 sedimentary rocks

Total = 90 + 45 = 135
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In Cliff’s impressive rock collection, there are half as many igneous 08 May 2023, 04:01
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