Quantitative Aptitude - Arithmetic Ability Questions

A can make a cupboard in 10 days and B can do it in 50 days. Along with C, they did the job in 6.25 days only. Then in how many days C alone can do the job?

Of the three numbers, the average of the first number and the second number is 37 more than the average of second number and third number. What is the difference between the first and the third number?

If Rajan purchase 21 pens for Rs 20 and sell all the pens at the rate of 20 pens for Rs 21, then what will be the profit percentage?

Ages of Lalu and Balu are in the ratio of 1 : 2. After 7 years their ages ratio changes to 3 : 5. The elder person age is

1/3 part of a certain journey is covered with the speed of 25 km/hr, 1/2 part of the journey is covered with the speed of 45 km/hr and the remaining part covered with the speed of 37.5 km/hr. What is the average speed (in km/hr) for the whole journey?

Working 5 hours a day, Shivam can read a book in 24 days. How many hours a day should he work so as to finish the same work in 8 days?

The points A(x,2), B(­2,1) and C(6,­3) are collinear. Find x?

If the perimeter of a semicircle is 108 cm, then find its area (in cm²).