9 cm
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The temperature decreased by 28%
Step-by-step explanation:
How did the temperature change if :
- At first it decreased by 60%
- Then increased by 80%
Assume that the temperature before decreasing is 100%
∵ The temperature before decreasing = 100%
∵ It decreased by 60%
→ Before decreasing : decreasing : after decreasing
→ 100% : 60% : 100% - 60% = 40%
∴ The temperature after decreasing = 40%
Assume that the temperature after decreasing is 100%
∵ The temperature after decreasing = 100%
∵ It increased by 80%
By using the ratio method
→ After decreasing : increasing : after increasing
→ 100% : 80% : 100% + 80% = 180%
→ 40% : : x%
By using cross multiplication
∴ 100% × x% = 40% × 180%
- Divide both sides by 100%
∴ x% =
∴ x% = 72%
∵ At first the temperature = 100%
∵ At last the temperature = 72%
∵ The first the temperature > the last the temperature
∴ The decreasing in temperature = 100% - 72% = 28%
The temperature decreased by 28%
Learn more:
You can learn more about ratio in brainly.com/question/2707032
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