G8 AMC practice 4

Lisa swims laps in the swimming pool. When she first started, she completed 12 laps in 30 minutes. Now she can finish 30 laps in 45 minutes. By how many minutes has she improved her lap time?

• 1

• 2

• 1/2

• 2/3

Alex gets 90% on a 20-problem test, 95% on a 40-problem test and 96% on a 25-problem test. If the three tests are combined into one 85-problem test, which percent is closest to her overall score?

• 92

• 93

• 94

• 95

Bob and Chan are reading the same 660-page novel. Bob reads a page in 30 seconds and Chan reads a page in 20 seconds. If Bob and Chan both read the whole book, Bob will spend how many more seconds reading than Chan?

• 7600

• 6600

• 12500

• 15200

Three friends, Alice, Bob and Chan are reading the same 660-page novel. Alice reads a page in 10 seconds, Bob reads a page in 30 seconds and Chan reads a page in 20 seconds. If they divide the book into three sections so that each reads for the same length of time, how many seconds will each have to read?

• 2600

• 1600

• 6800

• 3600

A cube with 4-inch edges is made using 64 cubes with 1-inch edges. Fifty-six of the smaller cubes are grey and eight are white. If the eight white cubes are placed at the corners of the larger cube, what fraction of the surface area of the larger cube is grey?

• 1/12

• 1/9

• 1/6

• 1/4

A singles tournament had six players: Alice, Betsy, Cathy, Debra, Emily, and Friday. Each player played every other player exactly twice, with no ties. If Alice won 8 games, Betsy won 6 games, Cathy won 4 games, Debra won 4 games and Emily won 4 games, How many games did Friday win?

• 1

• 3

• 2

• 4

An aquarium has a rectangular base that measures 120 cm by 60 cm and has a height of 70 cm. The aquarium is filled with water to a depth of 48 cm. A rock with a volume of 2016 cubic cm is then placed in the aquarium and completely submerged. By how many centimeters does the water level rise?

• 0.28

• 0.5

• 0.25

• 1.5

Points A, B, C, and D are midpoints of the sides of the larger square. The smallest square is formed the same way. If the largest square has an area of 160, what is the area of the smallest square?

• 30

• 35

• 24

• 40

Point D is the midpoint of both BC and AE of triangles ACB and ACE, respectively. The area of ACB IS 11 square units. Find the area of triangle CDE in square units.

• 4

• 4.5

• 5

• 5.5