Quantitative Aptitude - Arithmetic Ability Questions

Twenty one times of a positive number is less than its square by 100. The value of the positive number is

A factory buys 10 machines. 2 Machine­A, 3 Machine­B and rest Machine­C. Prices of the machines are Rs 95000, Rs 60000 and Rs 50000 respectively. What is the average cost of these machines?

A, B and C can do a job working alone in 12, 16 and 24 days respectively. In how many days they can do the job if they worked together?

A, B and C are employed to complete a work in Rs. 784. If A and B together complete 23/28 of the work. Calculate the wages (in Rs.) paid to C?

Z’s present age is 55 years. If 11 years ago, C’s age was 1/11 of Z’s age, then after how many years C’s age will become 37 years?

If 20 men working 8 hours per day can complete a piece of work in 21 days. How many hours per day must 48 men work to complete the same job in 7 days?

$$\begin{gathered} ∆ABC is similar to ∆PQR. If ratio of perimeters of ∆ABC and ∆PQR is 1:2 and \\ if PQ = 10 cm then what is the length of AB (in cm)? \end{gathered}$$

Yaman sold an item at a loss of 10%. If he had sold it for Rs.57 more, he would have made a profit of 20%. What should be the selling price of the item to make a profit of 30%?