Ratio and Proportion (Math for the Trades)

Ratio and Proportion (Math for the Trades)

by Mary Lett

​Ratio

​Special Ratios

Multiple Choice

Looking at the picture, what is the gear ratio? The arrow shows the driven gear.

• 4:6
• 6:4
• 2:3
• 3:2

Multiple Choice

Looking at the picture, what is the gear ratio? The arrow shows the driven gear.

• 4:24
• 1:6
• 2:12
• 1:9

Multiple Choice

The input gear has 6 teeth.
The output gear has 48 teeth.  The gear ratio is...

• 1:8
• 8:1
• 6:48

Multiple Choice

On the illustration, the number of the gear A teeth are 12, and the number of the gear B teeth are 48. Select one which shows correct gear ratio.

• 25

• 0.25

• 40

• 4

• 0.4

Multiple Choice

Calculate the compression ratio in a cylinder if the compression volume is 10 and the displacement is 80.

• 9:1
• 15:22:1
• 1500 PSI

​Proportion

Multiple Choice

Solve the proportion.

• k=5
• k=3.3333333
• k=60
• k=90

Multiple Choice

Solve the proportion.

• q=2
• q=9
• q=4.5
• q=6