Question

Difficulty: MediumRatios, Rates, and Proportions

A commercial bakery uses flour, sugar, and cocoa powder in a weight ratio of 5:3:25 : 3 : 2 to make a chocolate cake base. To create a specialty low-sugar version, the baker decreases the amount of sugar by 30%30\% and adds that exact reduced weight to the flour, leaving the amount of cocoa powder unchanged. What is the ratio of flour to sugar in the new specialty batch?

  1. A
    50:2150 : 21
  2. 59:2159 : 21Answer
  3. C
    59:10059 : 100
  4. D
    65:2165 : 21
  5. E
    53:2753 : 27

Answer

The ratio of flour to sugar in the new specialty batch is 59:2159 : 21.
In the original ratio 5:3:25 : 3 : 2, sugar accounts for 33 ratio units. Decreasing sugar by 30%30\% removes 30% of 3=0.930\% \text{ of } 3 = 0.9 units, leaving 30.9=2.13 - 0.9 = 2.1 units of sugar. Adding those 0.90.9 units to the original 55 units of flour increases flour to 5+0.9=5.95 + 0.9 = 5.9 units. The ratio of new flour to new sugar is 5.9:2.15.9 : 2.1, which multiplies by 1010 to yield 59:2159 : 21.

Step-by-Step Solution

1
Determine the initial ratio units for each component.
Flour = 55 units, Sugar = 33 units, Cocoa = 22 units.
The original weight ratio given is 5:3:25 : 3 : 2.
2
Calculate the reduction in sugar and the new sugar ratio amount.
Reduction = 3×0.30=0.93 \times 0.30 = 0.9 units; New Sugar = 30.9=2.13 - 0.9 = 2.1 units.
Sugar is reduced by 30%30\% of its original proportion.
3
Add the removed weight to the flour to find the new flour ratio amount.
New Flour = 5+0.9=5.95 + 0.9 = 5.9 units.
The weight subtracted from sugar is added directly to the flour.
4
Form the new ratio of flour to sugar and simplify to whole numbers.
5.9:2.1=59:215.9 : 2.1 = 59 : 21.
Multiplying both parts of the decimal ratio 5.9:2.15.9 : 2.1 by 1010 converts it into a simple integer ratio.

Key Concept

Adjusting part-to-part ratios by applying percentage changes to individual components and simplifying fractional ratios.
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