Q57 / 150 · MHT CET 2008 · Mathematics
Considering four sub-intervals, the value of $\int_{0}^{1} \frac{1}{1+x} d x$ by Trapezoidal rule, is
- A$0.6870$
- B$0.6677$
- Correct answerC$0.6977$
- D$0.5970$
Solution
\begin{array}{c|l|l}
\hline \boldsymbol{i} & \boldsymbol{x}_{\boldsymbol{i}} & \boldsymbol{y}_{\boldsymbol{i}}=\frac{\mathbf{1}}{\mathbf{1 +} \boldsymbol{x}_{\boldsymbol{i}}} \\
\hline 0 & 0 & 1 \\
1 & 0.25 & 0.8 \\
2 & 0.5 & 0.67 \\
3 & 0.75 & 0.571 \\
4 & 1 & 0.5 \\
\hline
\end{array}
Trapezoidal rule gives
$\begin{aligned} \int_{0}^{1} \frac{1}{1+x} d x=& \frac{h}{2}\left[y_{0}+2\left(y_{1}+y_{2}+y_{3}\right)+y_{4}\right] \\=& \frac{1-0}{2 \times 4}[1+2(0.8+0.67\\ & \\=& 0.6977 \end{aligned}$
Hence, the correct answer is option: 'C'.