ABC26GN0790 · Decimal Fractions
Subject: General Aptitude · Chapter: Decimal Fractions · Exam: · Marks: · Difficulty:
Solve $\left(41.99^{2}-18.04^{2}\right) \div ?=13.11^{2}-138.99$ [IBPS-Bank Spl. Officers (IT) Exam, 2015]
(a)48
(b)12
(c)72
(d)84
(e)128
Answer
Explanation
$\left\{(41.99)^{2}-(18.04)^{2}\right\} \div ?=(13.11)^{2}-138.99$ $$\begin{aligned} & \Rightarrow\left\{(42)^{2}-(18)^{2}\right\} \div ?=(13)^{2}-139\left\{\because a^{2}-b^{2}=(a+b)(a-b)\right\} \\ & \Rightarrow\{(42+18)(42-18)\} \div ?=169-139 \\ & \Rightarrow 60 \times 24 \div ?=30 \\ & \Rightarrow ?=\frac{60 \times 24}{30}=48 \end{aligned}$$
Explanation as extracted from the printed page; notation may be imperfect.
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