Based on the sales data of mobile phones in a showroom during a week (Monday: 200, Tuesday: 600, Wednesday: 450, Thursday: 600, Friday: 800, Saturday: 950, Sunday: 300), find the difference between the highest number of mobiles sold and the lowest number of mobiles sold in the given week.

In a data table, the production of rice for country Q and country R is 60 lakh tons and 54 lakh tons respectively. The production of wheat for country S and country T is 52 lakh tons and 52 lakh tons respectively. What is the ratio of the total production of rice of countries Q and R to the total production of wheat of countries S and T?

In a survey of 5 countries (P, Q, R, S, T), the rice production values are 40, 60, 54, 70, and 51 lakh tons respectively. What is the average production of rice (in lakh tons) across all 5 countries?