Because these scales are related linearly, we need to figure out the "slope" which will then be able to tell us how much one scale changes with 1 unit of movement on the other one.

The R-scale moves 18 (from 6 to 24 is 24-6=18) for every 30 (30 to 60 is 60-30=30) that the S-Scale moves. This is a 18/30 slope, or 3/5 slope.

Lets check to see if this is indeed the right slope.

R=6, S=30

R=9, S=35

R=12, S=40

R=15, S=45

R=18, S=50

R=21, S=55

R=24, S=60 <---Just like it should

If we're going to 100 from 60, that's a difference of 40, and if we go in increments of 5, that's 40/5 increments, or 8 increments, so on the other scale that goes in increments of 3, it's 8 * 3=24 more units, or 48 on the R-Scale = 100 on the S-Scale. Answer C.

alpha_plus_gamma wrote:

Jcpenny wrote:

A certain quantity is measured on two different scales, the R-scale and the S-scale, that are related linearly. Measurements on the R-scale of 6 and 24 correspond to measurements on the S-scale of 30 and 60, respectively. What measurement on the R-scale corresponds to a measurement of 100 on the S-scale?

A. 20

B. 36

C. 48

D. 60

E. 84

Note that scales are related "linearly"

y = mx + c

30 = m*6 + c

60 = m*24 + c

solving m =5/3, c =20

100 = 5/3 * x + 20

80 * 3/5 = x therefore x =48

C.

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J Allen Morris

**I'm pretty sure I'm right, but then again, I'm just a guy with his head up his a$$.

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