G8 AMC practice 3

 $a@b=\frac{a+b}{ab}$  If we have a formula as this for positive integers a and b, then what is 5@10?

•  $\frac{10}{3}$  

• 10

• 3

•  $\frac{3}{10}$  

What is the sum of the mean, median, and mode of the numbers 3, 4, 1, 4, 2, 5, 1, 4?

• 9.5

• 10

• 10.5

• 11.5

Which of the following figures has the greatest number of lines of symmetry?

• equilateral triangle

• square

• regular pentagon

• circle

Using only pennies, nickels, and quarters, what is the smallest number of coins Freddie would need so he could pay any amount of money up to 99 cents?

• 9

• 11

• 10

• 12

A car leaves a town traveling at 40 mph. Two hours later, a second car leaves the same town, on the same road, traveling 60 mph. The second car drives how many hours to overtake the first car?

• 2

• 1

• 1.5

• 4

Of the 640 balls in a large bag, 85% are red and the rest are blue. How many of the red balls must be removed from the bag so that 75% of the remaining balls are red?

• 250

• 500

• 275

• 256

The hundreds digit of a three-digit number is 7 more than the unit digit. The digit of the three-digit number is reversed, and the resting number is subtracted from the original three-digit number. What is the unit digit of the final result?

• 0

• 3

• 2

• 6

Five pepperoni circles will exactly fit across the diameter of a 10-inch pizza when placed as shown. If a total of 10 circles of pepperoni are placed on this pizza without overlap, what fraction of the pizza is covered by pepperoni?

• 1/2

• 2/5

• 4/5

• 2/3

The two circles are concentric circles with center C. Chord AB is tangent to the inner circle at D and AB=22. Find the area between the two circles.

• $144\pi$

• $100\pi$

• $121\pi$

• $169\pi$

what is the correct ordering of the three numbers,

• $2^{40}<4^{19}<3^{28}$

• $4^{19}<2^{40}<3^{28}$

• $4^{19}<3^{28}<2^{40}$

• $3^{28}<4^{19}<2^{40}$