The mean of 1, 3, 5, 7 and x is 4. Find the value of x

A man bought a second hand photocopying machine for ₦34,000. He serviced it at a cost of ₦2,000 and then sold it at a profit of 15%. What is the selling price?

There are 250 boys and 150 girls in a school. If 60% of the boys and 40% of the girls play football, what percentage of the school plays football?

Find the median of 2, 1, 0, 3, 1, 1, 4, 0, 1, and 2