Quantitative Aptitude - Arithmetic Ability Questions

The average of marks of 17 students in an examination was calculated as 71. But it was later found that the mark of one student had been wronglyentered as 65 instead of 56 and another as 24 instead of 50. The correct average is

Manoj can do a piece of work in 42 hours. If he is joined by Jayashree who is 100% more efficient, in what time they will finish the work together?

A can do a work in 36 days and B in 12 days. If they work on it together for 3 days, then what fraction of work is left?

The standard deviation of the set {10, 10, 10, 10, 10} is

If the selling price of an item is Rs 1000 after getting a discount of 20%, then what was the marked price (in Rs)?

Let A(O,-1), B(0,3) and C(2,1) be three points. Let   △1 be the area of the triangle ABC and △2 be the area of the triangle formed by the mid points of the sides of the triangle whose vertices are A, B and C such that △1=1 ,△2=x Find the value of x .

When a number is increased by 24, it becomes 110% of itself. What is the number?

Find the odd word/letters/number pair from the given alternatives.