What is the percentage of the earth's surface covered by

Choose the Venn diagram which best illustrate the three given classes.

Dog, Animal, Pet. 

What is the smallest number that should be subtracted from 1798425 so that the resulting number is divisible by 8?

The nine digit number 9x48879y4 is divisible by 88. Find the value of √xy, given that x < 8 and y < 8.

If '+' means '-' , '-' means 'x' , 'x' means '÷' , '÷' means '+' , then what will be the value of ' 500 x 50 - 20 ÷ 50 + 40 ' = ? 

Find the unit digit of 33²³ + 42³⁵

The respective ages of a mother and her daughter are 45 and 9 years. In how many years will the mother be thrice as old as her daughter?

If a sum invested at compound interest of 25% p.a., compounded annually becomes Rs. 18,750 after 2 years, then find the sum invested.