Quantitative Aptitude - Arithmetic Ability Questions

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

What approximate value should come in place of the question mark (?) in the following questions? (You are not expected to calculate the exact value.)

21.003 × 39.998 –209.91 = 126× ?

If  tan2θ + cot2θ = 2, then what is the value of 2sec θ cosec θ?

The population of a town is 200000. It increases annually at the rate of 10%. What will be the population after 2 years?

If the present ages of a father and his son are 48 years and 28.8 years old respectively, then the father can say to his son, "I was ......... of your present age when you were born".

A right triangular pyramid XYZB is cut from cube as shown in figure. The side of cube is 16 cm. X, Y and Z are mid points of the edges of the cube. What is the total surface area (in sq.cm) of the pyramid?

In what ratio must a mixture of 20% milk strength be mixed with that of 60% milk strength so as to get a new mixture of 25% milk strength ?

The costs of daily ticket of local train is Rs 130 and Monthly Pass costs Rs 3091.40. If I buy the Monthly Pass and travel for 29 days in a month than I save (in percentage)?