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Solution |
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1) A grocery store sells three different-sized cans of orange juice. A 6-oz can costs 55 cents. A 16-oz can costs $1.15. A 32-oz can costs $2.79. Which is the best buy?
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6-oz can costs 55/6 = 9.167 cents/oz
16-oz can costs 115/16 = 7.1875 cents/oz
32-oz can costs 279/32 = 8.71875 cents/oz
The 16-oz can is the best buy.
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2) In Kendra's school, 2 out of every 5 seventh graders went to a movie theater over the weekend. If there are 80 students in the seventh grade, how many of them saw a movie?
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1/5 of 80 is 16 students.
2/5 of 80 is 32 students.
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3) A food stand buys ice cream cones in packages of 8. Each carton of ice cream will make 12 cones. What is the least number of packages of ice cream cones and cartons of ice cream that need to be bought to have no leftover ice cream and no leftover cones?
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Method 1 (write out multiples):
Multiples of 8: 8 16 24 32 40 48
Multiples of 12: 12 24 36 48 60 72
The LCM of 8 and 12 is 24.
(48 is also a multiple, but it is not "least")
Therefore the least number of packages of cones is
3 (packages of 8)
and the number of cartons of ice cream is
2 (packages of 12)
Method 2: Use the LCM-GCF equation:
LCM(8,12) = (8 x 12) / GCF(8,12)
The GCF of 8 and 12 is 4
LCM(8,12) = 96/4 = 24
Therefore the least number of packages of cones is 3 (packages of 8)
and the number of cartons of ice cream is 2 (packages of 12)
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