CSATNumber System & SeriesArithmetic Geometric Progression and Averages2021

From January 1, 2021, the price of petrol (in Rupees per litre) on mth day of the year is 80 + 0.1m, where m = 1, 2, 3, ..., 100 and thereafter remains constant. On the other hand, the price of diesel (in Rupees per litre) on nth day of 2021 is 69 + 0.15n for any n. On which date in the year 2021 are the prices of these two fuels equal ?

A

21st May

B

20th May

C

19th May

D

18th May

Correct Answer: Option B

Explanation

1. **Check the Boundary (Day 100):** The problem states Petrol price changes behavior after Day 100. Let's see the status exactly at this boundary. This is the 'Boundary Condition' check [36], [43]. - Petrol

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