Direction : What should come in place of the question (?) in the following question.

$$ {\sqrt{441}}+ {(71)^{2}} -{(?)^{2}}=2707 $$

The ratio of present ages of Shankar and Mohan is 7: 8 respectively. Four year hence this ratio becomes 9: 10 respectively. What is Shankar’s present age in years?

Aman and Ajay can build a wall in 9 days and 12 days respectively. In how many days can they finish the work if they work together?

Find the value of k in $$ {26\over 21}:{24\over 9 }::k :{14\over 13}$$

Umesh earns a simple interest of ₹1,600 on a certain sum in two years at the rate of 4% per annum. How much more interest would he have earned if he had invested the same sum at 4% interest per annum, compounded annually?

Ratio of the employees in company A to B is 6: 5 and the number of employees in C to A is 13: 10. If the ratio of the number of male to female employees in A, B and C is 7: 5, 2: 3 and 7: 6 respectively, then the number of female employees in all the companies together is approximately what percent of the total number of employees in all the companies together?

If Arun purchases 11 articles for Rs.10 and sold all the articles at the rate of 10 for Rs.11, the profit percentage will be.

Two people A and B started their journey from P to Q and Q to P respectively. After crossing each other, A and B completed the remaining part of their journey in 3 hour 20 mins and 4 hours 48 mins respectively. If the speed of B is 80 km/hr, then find the speed of A in (km/ hr)?