Quantitative Aptitude - Arithmetic Ability Questions

In the following question, select the odd letter/letters from the given alternatives.

In the following question, select the odd letter/letters from the given alternatives.

If the standard deviation of a population is 6.5, what would be the population variance?

If 3x2 - ax + 6 = ax2 + 2x + 2 has only one (repeated) solution, then the positive integral solution of a is

If P : Q : R = 6 : 7 : 8 and R : S = 3 : 5, then what is P : S?

A shopkeeper marks up his wares by 60% and offers 25% discount. What will be the selling price (in Rs) if the cost price is Rs 1600?

The simple and compound interest that can be earned in two years at the same rate is Rs 1,000 and Rs 1,040 respectively. What is the rate (percent per annum) of interest?

P, Q and R are channels which discharge solutions A,B and C respectively in a tank. When the tank is empty and all the three channels are opened what is the proportion of the solution C in the tank after 3 minutes, if the channels P, Q and R can fill the tank from empty to full in 30 minutes and 20 minutes and 10 minutes respectively when they are opened one at a time.