What approximate value should come in the place of question mark (?) in the following question? (You are not expected to calculate the exact value) 55% of 99.999 + ?2 = 56% of 850 – 20% of 150

What approximate value should come in the place of question mark (?) in the following question? (You are not expected to calculate the exact value) 55% of 99.999 + ?2 = 56% of 850 – 20% of 150 Correct Answer 20

Rules of Approximation:

1. If a number has digits to the right of the decimal less than 5, then just drop the digits to the right of the decimal. The number so obtained will be the approximated value.

2. If a number has digits to the right of the decimal more than 5, then just drop the digits to the right of the decimal and raise the remaining number by '1'.The number so obtained will be the approximated value.

Concept:

In this type of question, we are expected to calculate the approximate value (not exact value), so we can replace the given numbers by their nearest perfect places which makes the calculation easy.

55% of 99.999 + ?² = 56% of 850 – 20% of 150

Taking approximate value, we get

55% of 100 + ?² = 56 % of 850 – 20% of 150

Follow BODMAS rule to solve this question, as per the order given below, 

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⇒ (55 ÷ 100 × 100) + ?² = (56 ÷ 100 × 850) – (20 ÷ 100 × 150)

⇒ 55 + ?² = 476 – 30

⇒ 55 + ?² = 446

⇒ ?² = 446 - 55

⇒ ?² = 391

∴ ? ≈ 20