Abag contains some orange, blue, red and yellow marbles. each student is allowed to pick two marbles. how many students must there be so that at least two students pick marbles of the same colour?

Omar is going on a road trip! the car rental company offers him two types of cars. each car has a fixed price, but he also needs to consider the cost of fuel. the first car costs $90 to rent, and because of its fuel consumption rate, there's an additional cost of s0.50 per kilometer driven.

Alicia puts $400 in a bank account. each year the account earns 5% simple interest. how much money will be in her bank account in six months?

You work in a hospital that has 9 floors. you need to see 3 patients on each floor. how many patients do you need to see in all?