Secondary → Number → Ratio \& Proportion464d: Determine an amount given a change in aWatch Worked Exampleratio where one part is changing.Q1Q2Q3Q4Q5Q6Q7Q8Q9Q10Q11Q12Q13Q14Q15Q16Q17Q18Q19Q20COMPLETION60%There are blue counters and black counters in a bag in the ratio 5:134 blue counters are removed and the ratio becomes 3:4Work out how many black counters there are in the bag.black countersSubmit Answer
Q. Secondary → Number → Ratio \& Proportion464d: Determine an amount given a change in aWatch Worked Exampleratio where one part is changing.Q1Q2Q3Q4Q5Q6Q7Q8Q9Q10Q11Q12Q13Q14Q15Q16Q17Q18Q19Q20COMPLETION60%There are blue counters and black counters in a bag in the ratio 5:134 blue counters are removed and the ratio becomes 3:4Work out how many black counters there are in the bag.black countersSubmit Answer
Initial ratio setup: Initial ratio of blue to black counters is 5:1. This means for every 5 blue counters, there is 1 black counter. Let the number of black counters be b. Then, the number of blue counters is 5b.
New ratio setup: After removing 34 blue counters, the new ratio of blue to black counters becomes 3:4. So, the new number of blue counters is 5b−34. The equation based on the new ratio is b5b−34=43.
Solve for b: Solve the equation (5b−34)/b=3/4 for b. Cross-multiplying gives 4(5b−34)=3b. Simplifying, 20b−136=3b.
Final solution: Further simplifying, 20b−3b=136, 17b=136, b=17136, b=8.
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