Guess and Check

Guess and Check Tables as a problem solving strategy • Read the problem carefully. Make notes or sketch a picture to organize the information in the problem. • Look at the question being asked. Set up a table with clearly labeled columns. Let your last column be your goal number. Leave extra space for more columns in case you need them. • Make a guess and calculate the entry for each column. Make note in the last column whether your guess was too high or too low. • Adjust your next guess based on whether your last guess was too high or too low. • Write the answer in a complete sentence.

Note: Guess and Check Tables can also be used to transition students into writing equation. After performing the same series of calculations repeatedly, students may substitute a variable for their guess in order to create an equation.

Example: A fruit salad consists of blueberries, raspberries, grapes, and cherries. The fruit salad has a total of 280 pieces of fruit. There are twice as many raspberries as blueberries, three times as many grapes as cherries, and four times as many cherries as raspberries. How many cherries are there in the fruit salad?

# of blueberries # of raspberries # of cherries # of grapes Total = 280 10 2(10) = 20 4(20) = 80 3(80) = 240 10 + 20 + 80 + 240 = 350 too high 5 2(5) = 10 4(10) = 40 3(40) = 120 5 + 10 + 40 + 120 = 175 too low 8 2(8) = 16 4(16) = 64 3(64) = 192 8 + 16 + 64 + 192 = 280 x 2(x) = 2x 4(2x) = 8x 3(8x) = 24x x + 2x + 8x + 24x = 280