For the following questions answer them individually
A boat goes downstream at the rate of 9 kmph and upstream at the rate of 6 kmph. Find the speed of current.
A person sells half of his goods at 20% profit and remaining half at 30% profit. What is his overall gain per cent in the whole transaction ?
The average age of five persons is 60 years. The average age of first four persons is 40 years. What is the age of the fifth person ?
Five years ago, the ratio between ages of Meena and Sita was 3 : 4. After five years from now the ratio between their ages will be 5 : 6. Find the present age of Meena ?
The average of five positive numbers is 470. The average of first two numbers is 720 and the average of the last two numbers is 150. What is the third number ?
What will come in place of the question mark (?) in the following questions?