Cars n' trucks

lets the revenue from car sales be C and Trucks be T in 1996
Therefore, with the data provided the revenues in 1997 will be

Cars => (1-11/100)C = (0.89)C
Trucks => (1+7/100)T = (1.07)T
The total revenue => (1 + 1/100)(C+T) = 1.01(C+T)

Combining the data above we get

0.89C + 1.07T = 1.01(C + T)
=> 0.06T = 0.12 C
=> C/T = 0.06/0.12 = 1:2

alex.gellatly wrote:A certain company that sells only cars and trucks reported that revenues from car sales in 1997 where down 11 percent from 1996 and revenues from truck sales in 1997 were up 7 percent from 1996. If total revenues from car sales and truck sales in 1997 where up 1 percent, what is the ratio of revenue from car sales in 1996 to revenue from truck sales in 1996?

1:2
4:5
1:1
3:2
5:3

This is a MIXTURE problem: an 11% decrease in car revenue and a 7% increase in truck revenue are being combined to form a MIXTURE with an overall revenue increase of 1%.
The following approach is called alligation.
It's a very good way to handle MIXTURE PROBLEMS.

Let C = car revenue and T = truck revenue.

Step 1: Plot the 3 percentages on a number line, with the two starting percentages (-11% and +7%) on the ends and the goal percentage (+1%) in the middle.
C(-11%)--------------------(+1%)--------T(+7%)

Step 2: Calculate the distances between the percentages.
C(-11%)----------12---------(+1%)----6----T(+7%)

Step 3: Determine the ratio in the mixture.
The ratio of C to T in the mixture is the RECIPROCAL of the distances in red.
C:T = 6:12 = 1:2.

The correct answer is A.

For two other problems that I solved with alligation, check here:

https://www.beatthegmat.com/ratios-fract ... tml#484583