The sum of the reciprocals of A’s ages (in years) 2 years ago and 2 years from now is. The present age of A is?
- 4 years
- 5 years
- 7 years
- None
Explanation
Calculation:
Let, the present age of A = A
2 years ago, his age = A - 2
2 years from now, his age = A + 2
According to the question,
⇒ = 1/A - 2 + 1/A + 2 = 2/3
⇒ 3(A + 2 + A - 2) = 2(A + 2)(A - 2)
⇒ 6A = 2(A2 - 22)
⇒ A2 - 3A - 4 = 0
⇒ A2 + A - 4A - 4 = 0
⇒ A(A + 1) - 4(A + 1) = 0
⇒ (A - 4)(A + 1) = 0
⇒ A = 4 or -1
Since, age can't be negative A = 4
∴ The present age of A is 4 years.
Related MCQs
- 25%
- 30%
- 35%
- None of these
اس سوال کو وضاحت کے ساتھ پڑھیں
ایک طالب علم معیاری ٹیسٹ میں 84 ویں فیصد پر ہے۔ اس کا سب سے زیادہ قابل دفاع مطلب کیا ہے؟
- About 84% of the reference group scored no higher
- The learner answered exactly 84% of the items correctly
- The learner's raw score is 84 points above the mean
- Exactly 84% of all test items were easier for the learner
اس سوال کو وضاحت کے ساتھ پڑھیں
