Question

The length and breadth of a field are measured $l=(120\pm 2)m$ and $b=(100\pm 5)m$ respectively. What is the area of the field?

• A. $(1.2\pm 0.08)\times {10}^4{m}^2$
• B. $(1.2\pm 0.04)\times {10}^4{m}^2$
• C. $(1.6\pm 0.08)\times {10}^4{m}^2$
• D. $(1.6\pm 0.04)\times {10}^4{m}^2$

Answer 1

The correct option is A

$(1.2\pm 0.08)\times {10}^4{m}^2$

$\frac{\Delta A}{A}=\frac{\Delta l}{l}+\frac{\Delta b}{b}=(\frac{2}{120}+\frac{5}{100})=0.0667\Delta A=0.0667\times AA=12000m^2\Delta A=800.4Area=A\pm \Delta A=(12000+800.4)=(1.2\pm 0.08)\times {10}^4{m}^2$