77.6k views
3 votes
Exercise #6: Demarco is trying to determine how many pennies he has without having to count

them. He first weighs 20 pennies and finds they have a total weight of 54 grams. He then weighs
all the pennies and finds they weigh a total of 918 grams.
(a) Determine how much a single penny
weighs, i.e. the grams per penny.
(b) Use your answer from (a) to determine
how many pennies Demarco has.

User Uncle Dino
by
4.3k points

1 Answer

6 votes

Explanation:

20 pennies weigh 54 grams.

what is the weight of a single penny ?

well, 1/20 of the weight of the 20 pennies.

so,

54/20 = 27/10 = 2.7 grams

all his pennies weigh 918 grams.

how many pennies are there ?

as many as the times the weight of a single penny fit into the total weight.

so,

918 / 2.7 = 9180/27 = 340

he has 340 pennies.

User Lessmore
by
4.6k points