Histogram or age chart: count in one class range is what percent more or less than another range

This type of question, asked 3 times: 15 Nov 2020 Tier II, 29 Jan 2022 Tier II, 3 Feb 2022 Tier II. All 3 questions below, oldest first.

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Question 1
15 Nov 2020 Tier II
7 $Study the given graph and answer the question that follows. The number of patients aged 10 or more years but below 40 years is what per cent less than the number of patients aged 50 or more years but below 80 years?$
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Question 2
29 Jan 2022 Tier II
53 $Study the given histogram and answer the question that follows. The number of persons weighing 55 kg or more but less than 75 kg is what percentage more than the number of persons weighing 80 kg or more but less than 100 kg (correct to one decimal place)?$
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Question 3
3 Feb 2022 Tier II
95 $Study the given histogram and answer the question that follows. The total number of neon lamps having lifetime of 800 or more hours is approximately what percentage more than the total number of neon lamps having lifetime of 400 or more hours but less than 800 hours?$
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Question 1