Quantitative Aptitude - Arithmetic Ability Questions

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× ?

Point A divides segment BC in the ratio 1:3. Co-ordinates of B are (4,-4) and C are (0,6). What are the co-ordinates of point A?

Tanzeem spent 1/5 of his salary on his friends, 1/10 of his salary on accommodation and 1/4 of his salary on savings. If he has Rs. 1800 left in his wallet,then find his total expenditure on accommodation and savings.

Of the 3 numbers whose average is 22, the first is 3/8th the sum of other 2. What is the first number?

The expression 52n –23n has a factor?

∆XYZ is right angled at Y. If tanX = 24/7, then what is the value of cotZ ?

In a triangle the length of the side opposite the right angle is 9√3 cm, what is the length of the side opposite to the angle which measures 30 degree?

A and B can together complete a task in 18 hours. After 6 hours A leaves. B takes 36 hours to finish rest of the task. How many hours would A have taken to do the task if he worked alone?