Explanation
Khilona earned scores of 97, 73 and 88 respectively in her first three examinations. If she scored 80 in the fourth examination, then her average score will be
{\textbf{Step -1: Finding number of work units for the first case}}{\text{.}}
{\text{Total 24 men work for 8 hours a day and takes a total of 15 days to complete it}}{\text{.}}
{\text{So total work units}} = 24 \times 8 \times 15 = 2880
{\text{Thus, for the first case, it's a total of 2880 work units}}{\text{.}}
{\textbf{Step -2: Finding number of days for the second case}}{\text{.}}
{\text{Let it takes }}x{\text{ days for the worker to complete the task, so we can write}}
{\text{Number of work units}} = 20 \times 9 \times x = 180x
{\text{Also, the work is same so the work units must be same}}
{\text{So, equating the work units for the two cases, we get}}
\Rightarrow 2880 = 180x
\Rightarrow x = \dfrac{{2880}}{{180}} = 16
{\textbf{Thus, it will take 16 days for the 20 workers to complete the work}}{\textbf{. Thus, option B }}\textbf{is correct.}
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