A set has exactly five consecutive positive integers starting with 1. What is the percentage decrease in the average of the numbers when the greatest one of the numbers is removed from the set?

A total of x feet of fencing is to form three sides of a rectangular yard. What is the maximum possible area of the yard in terms of x?

The present ages of M and N are in the ratio of 6: 4. Five years age, age, their ages were in the ratio of 5: 3. How old is M now?

If p + q = 7 and pq = 12 , then what is the value of $\frac{1}{p^2} + \frac{1}{q^2} =?$

There are 4 cows and 4 goats are in a field. If two of the animals are selected at random, what is the probability that both will be cows?

Group a has 20 members and Group B has 28. If a total of 42 people belong to the two groups, how many people belong to both groups?