Answer:
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Formula: 1 Mark
Steps: 1 Mark
Answer: 1 Mark
Number of questions Aarush used to solve initially = 4 questions in 16 minutes
Time needed to solve a question = $\frac{16}{4}$ = 4 minutes
Number of questions Aarush can solve after practising = 6 questions in 18 minutes
Time needed to solve a question = $\frac{18}{6}$ = 3 minutes
Decrease in time to solve a single question = 4 - 3 = 1 minutes.
Therefore, the percentage decrease is given by
Decrease Percent = $\frac{\text{amount decreased}}{\text{Original or base}}\times 100$
On substituting the values, weget:
Decrease in percentage = $\frac{1}{4}\times 100$ = 25%
Hence, after practising Aarush reduced 25% of the time to solve a single question.