What should come in place of the question mark (?) in the following question?…
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What should come in place of the question mark (?) in the following question?
165 ÷ 15 × 13 + (2/7) of 91 - ? = 50% of 320
Answer: D. 9 — CONCEPTFor numerical expressions, division and multiplication are performed from left to right before addition and subtraction. A fraction “of” a number means…
- A.
5
- B.
6
- C.
7
- D.
9
Attempted by 10 students.
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Correct answer: D
CONCEPT
For numerical expressions, division and multiplication are performed from left to right before addition and subtraction. A fraction “of” a number means multiplication, and a percentage means a fraction out of 100.
An unknown in an equation is isolated with inverse operations while keeping both sides equal.
APPLICATION
Evaluate the division and multiplication from left to right: 165 ÷ 15 = 11, and 11 × 13 = 143.
Evaluate the fractional term: (2/7) of 91 = (2/7) × 91 = 26.
Combine the known terms on the left: 143 + 26 = 169, so the equation is 169 − ? = 50% of 320.
Evaluate the right side: 50% of 320 = (50/100) × 320 = 160.
Isolate the unknown: 169 − ? = 160, so ? = 169 − 160 = 9.
CROSS-CHECK
Substituting 9 gives 169 − 9 = 160, which is the same as 50% of 320.
Therefore, the value of the question mark is 9.