Question

Compute the following difference

$(11.3\times 10.7)-(11.7\times 10.3)$

• A. 0.8
• B. 0.2
• C. 0.6
• D. 0.4

Answer 1

The correct option is D

0.4

The given expression

$(11.3\times 10.7)-(11.7\times 10.3)$

$=(11+0.3)(11-0.3)-(11+0.7)(11-0.7)$

$=[{11}^2-(0.3{)}^2]-[{11}^2-{0.7}^2]$

$={11}^2-{0.3}^2-{11}^2+{0.7}^2$

$={0.7}^2-{0.3}^2$

$=(0.7+0.3)(0.7-0.3)$

$=1\times 0.4$

$=0.4$