Two bacteria colonies are cultivated in a laboratory. The first colony has a doubling time of 2 hours (h) and the second a doubling time of 3 h. Initially, the first colony contains 1000 bacteria and the second colony 3000 bacteria. At what time t will the sizes of the colonies be equal?

Joni planted two tree saplings in their garden on the same day. One tree sapling started out 25 inches tall and grew at a rate of 1.5 inches per week. Another tree sapling started out 35 inches tall and grew at a rate of 1 inches per week. After how many weeks were the two tree saplings the same height? weeks How tall were the saplings at this time? inches

Tree x has grown from 2 feet to 4 feet in one year. Within the same time tree Y grows from 3 feet to 5 feet. Which tree is taller after one year? Tree X grew by how many feet? Tree Y grew by how many feet? The height of tree X is how many times larger than its original height? Tree Y is how many times larger than its original height?

Two classmates have decided to read all the volumes in a popular series of books. Mia has already read 12 volumes and will continue to read new ones at a rate of 1 volume per week. Beth, who hasn't started reading the series yet, will read 4 volumes per week. At some point, Beth will catch up with Mia and they will be reading the same book. How long will that take? How many volumes will each girl have read by then? In ? weeks, the girls will each have read ? volumes in the series.