AMC 8 Daily Practice Round 3

Complete problem set with solutions and individual problem pages

Problem 1 Easy

Lucy wants to make a drink, which is made by sugar, salt, and water. The sugar concentration of the drink should be 8%, and the salt concentration should be 3%. She adds 24 grams of sugar and some grams of salt to the cup. How many grams of water does Lucy need?

  • A.

    267

  • B.

    300

  • C.

    333

  • D.

    400

  • E.

    433

Answer:A

24 \div 8% = 300

300 \times 3% = 9

300-24-9=267

Link Problem
Problem 2 Medium

How many four-digit numbers are divisible by 19?

  • A.

    390

  • B.

    430

  • C.

    473

  • D.

    474

  • E.

    475

Answer:D

Let k be any positive integer so that 19k is a multiple of 19. For the smallest four-digit number, 19k>1000 and k>\frac{1000}{19}\approx 52.6. For the greatest four-digit number, 19k < 9999 and k < \frac{9999}{19}\approx 526.26. The number k can be in the range 53 to 526. Thus, there are 474 numbers in total.

Link Problem
Problem 3 Easy

In the grid below, the distance between each two neighboring points is 1. What is the area of the shaded quadrilateral?

  • A.

    12

  • B.

    13

  • C.

    14

  • D.

    15

  • E.

    16

Answer:B

5\times5-5\times3\times\frac12-5\times1\times\frac12-2\times2\times\frac12=13

Link Problem
Problem 4 Easy

The side length of a triangle are three consecutive integers. The length of the longest side is \frac{2}{5} of the perimeter of the triangle. What is the length of the longest side?

  • A.

    4

  • B.

    5

  • C.

    6

  • D.

    7

  • E.

    8

Answer:C

Let n, n+1, and n+2 be the lengths of the sides of the triangle. Then the perimeter of the triangle is n+\left( n+1 \right)+\left( n+2 \right)=3n+3. Using the fact that the length of the longest side is \frac25 of the perimeter, it follows that: 0.4\left( 3n +3 \right)=n+2\Rightarrow n=4. The longest side is n+2=4+2=6. Thus, answer \left( \text{C} \right)6 is correct.

Link Problem
Problem 5 Easy

Yesterday was Saturday. Alice set out from home to see her grandmother. She walked for two hours in a straight line at a fixed speed. After arriving at grandmother's home, Alice spent two hours eating lunch and chatting with her. Then Alice took the bus back home. Taking the bus is twice as fast as walking. During the process, the relationship between Alice's distance from home (d) and time (t) is            .

  • A.

  • B.

  • C.

  • D.

  • E.

Answer:C

In the first two hours, Alice walked to her grandma's home, then she stayed in grandma's house for two hours. Starting from t=4, she took the bus back home and the speed was twiced. So the answer is C.

Link Problem
Table of Contents
  • 1
  • 2
  • 3
  • 4
  • 5