Multiple choice

A number is first increased by 40% and then decreased by 25%, again increased by 15% and then decreased by 20%. What is the net increase/decrease per cent in the number?

  1. 7.2% decrease

  2. 6.4% increase

  3. 3.4% increase

  4. 3.4% decrease

  5. None of the above
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Let the initial number be 100. After 40% increase: 140. After 25% decrease: 140 * 0.75 = 105. After 15% increase: 105 * 1.15 = 120.75. After 20% decrease: 120.75 * 0.8 = 96.6. The net change is 100 - 96.6 = 3.4% decrease.

AI explanation

To find the net percentage change, apply the successive percentage change formula or multiply the respective growth factors. The calculation is 1.40 * 0.75 * 1.15 * 0.80 = 0.966. Comparing this to the initial value of 1 gives a net decrease of (1 - 0.966) * 100 = 3.4 percent. The result is a 3.4% decrease.

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