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Mathematics · 2022 · 2 marks
CBSE 2022 · Region 4 · Set 1 · Q1
The mode of a grouped frequency distribution is $\displaystyle 75$ and the modal class is $\displaystyle 65$-80. The frequency of the class preceding the modal class is $\displaystyle 6$ and the frequency of the class succeeding the modal class is $\displaystyle 8$ . Find the frequency of the modal class.
Marking-scheme solution
Mode = $\displaystyle 75$, Modal class = $\displaystyle 65$-$\displaystyle 80$
\[l=65 f_{0}=6, f_{2}=8
\]
Mode \(\displaystyle =l+\frac{f_{1}-f_{0}}{2 f_{1}-f_{0}-f_{2}} \times h\)
\[75=65+\left(\frac{f_{1}-6}{2 f_{1}-6-8}\right) \times 15
\]
\(\displaystyle 4 f_{1}-28=3 f_{1}-18 \Rightarrow f_{1}=10\)
∴ Frequency of modal class is 10.
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CBSE Class 10 Mathematics past-paper question from the 2022board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.