Quantitative Aptitude - Arithmetic Ability Questions

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

P and Q can do a project in 6 and 12 days respectively. In how many days can they complete 25% of the project if they work together?

Radius of base of a hollow cone is 8 cm and its height is 15 cm. A sphere of largest radius is put inside the cone. What is the ratio of radius of base of cone to the radius of sphere?

If 1 + (1/2) + (1/3) + ... + (1/20) = k, then what is the value of (1/4) + (1/6) + (1/8) + ... + (1/40)?

If secA - tanA = x, then the value of x is

A number is increased by 84, it becomes 107% of itself. What is the number?

A tent is to be built in the form of a cylinder of radius 10 m surmounted by a cone of the same radius. If the height of the cylindrical part is 5 m and slant height of the conical part is 15 m, how much canvas will be required to build the tent? Allow 20% extra canvas for folding and stitching. (Take π = 22/7)

On a machine there is 10% trade discount on the marked price of Rs 2,50,000. But the machine is sold at Rs 2,16,000 after giving a cash discount. How much is this cash discount (in %)?