Warm-Up
Exam 3 #11
Give two reasons why Vance’s reasoning is wrong
Hint: Compare to a landmark and use equivalent fractions.
Student Errors• 7/8 + 3/32 + 1/16 is less than 1
because 7/8 is almost 1, and 1/16 is about 0, and 3/32 is about 0, so almost 1 + 0 + 0 is less than 1.
Student Errors• 8 3/4 • 2 7/8 • Find a common denominator:• 8 6/8 • 2 7/8 = 16 42/64 which is
simplified to 16 21/32.
Student Error• 4 7/8 ÷ 8 7/8 = (4 ÷ 8) ÷ (7/8 ÷ 7/8) =
1/2 ÷ 1 = 1/2
Student Error• 25 - 1/2 = • 25
- 1/2 25 1/2
Student Error• 29 1/7 - 16 4/7• 29 1/7 = 28 11/7
- 16 4/7 = 16 4/7 12 7/7 = 13.