If 3²⁰¹⁹ is divided by 10, then what is the remainder?

The number 3798125P369 is divisible by 7. What is the value of the digit P?

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

A biology class at Central High School predicted that a local population of animals will double in size every 12 years. The population at the beginning of 2021 was estimated to be 50 animals. If P represents the population n years after 2021, then which of the following equations represents the class model of the population over time?