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GATE 2020 MT – Question 52

Engineering Mathematics · Numerical methods · 2 marks · Numerical answer

Use the trapezoidal rule with two equal intervals to approximate $\int_0^1e^{-x^2}dx$, to 2 decimal places.

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Correct answer: 0.71 to 0.75

Explanation

With h = 0.5, the nodes are 0, 0.5 and 1. The composite trapezoidal approximation is $I\approx(h/2)[1+2e^{-0.25}+e^{-1}]=0.73137$. To two decimals this is 0.73. The middle node is weighted twice because it belongs to both trapezoids.

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