Question

If $r$ is a real number such that $|r|<1$ and if $a=5(1-r),$ then

• A. $0<a<5$
• B. $-5<a<5$
• C. $0<a<10$
• D. $0\le a<10$
• E. $-10<a<10$

Answer 1

Answer: (C)

$\because$ $|r|<1$
$\Rightarrow$ $-1<r<1$
Also, $a=5(1-r)$
$\Rightarrow$ $0<a<10$
$\left(\begin{array}{rl}& \because atr=-1,a=10\\ & andatr=1,a=0\end{array}\right)$