Finding a ratio after removing from one quantity Revision Card

Start with actual amounts and identify the category being reduced.

Start with actual amounts and identify the category being reduced.
Subtract only from that category. Check that the remaining amount is not negative.
Write the new ratio and divide all parts by their highest common factor.

Example 1

A bag contains 6 red counters and 9 blue counters. 1 red counter is removed. Find the new ratio of red to blue.

Change the red amount.

Blue stays unchanged.

Write red : blue using the new amounts.

A bag contains 12 red counters and 16 blue counters. 2 red counters are removed. Find the new ratio of red to blue.

Change the red amount.

Blue stays unchanged.

Write red : blue using the new amounts.

Remember
Use the worked steps to check your method, not just the final answer.

Question 1

A bag contains 20 red counters and 25 blue counters. 3 red counters are removed. Find the new ratio of red to blue.

Check answer

Change the red amount.

Blue stays unchanged.

Write red : blue using the new amounts.

Question 2

A bag contains 30 red counters and 36 blue counters. 4 red counters are removed. Find the new ratio of red to blue.

Check answer

Change the red amount.

Blue stays unchanged.

Write red : blue using the new amounts.

Question 3

A bag contains 42 red counters and 49 blue counters. 5 red counters are removed. Find the new ratio of red to blue.

Check answer

Change the red amount.

Blue stays unchanged.

Write red : blue using the new amounts.

Question 4

A bag contains 21 red counters and 24 blue counters. 6 red counters are removed. Find the new ratio of red to blue.

Check answer

Change the red amount.

Blue stays unchanged.

Write red : blue using the new amounts.

Question 5

A bag contains 32 red counters and 36 blue counters. 7 red counters are removed. Find the new ratio of red to blue.

Check answer

Change the red amount.

Blue stays unchanged.

Write red : blue using the new amounts.