Quantitative Aptitude - Arithmetic Ability Questions

Dodecahedron has 30 edges. How many vertices does it have?

Two pipes X and Y can individually fill a tank in 48 and 72 min respectively. If they are opened simultaneously, how long will it take for the tank to fill? 

10 people could complete a task in 8 days. After 4 days, 2 of the workers left. How many days from then did it take to complete the task?

What is the equation of the line which has 3/2 and -­4/7 as x and y intercept respectively?

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

The compound interest on Rs. 4000 for 4 years at 10% per annum will be

A bank offers 15% compound interest per half year. A customer deposits Rs 7200 each on 1st January and 1st July of a year. At the end of the year, the amount he would have gained by means of interest is

If three successive discounts of 20%, 30% and 40% are given, then what will be the net discount (in percentage)?