# 7.9: Coin Stumpers

**Coin Stumpers – Reason Proportionally with Metric Measurements**

**Teacher Notes**

Students reason proportionally about weights of coins in grams. They use those weights to solve multi-step problems. All weights are given to the nearest tenth of a gram.

The *Extra for Experts* include the values of the coins as an additional factor to consider in the problem solutions.

**Solutions:**

**Coin Stumpers 1**

2.3 grams

50 nickels are grams, or 250 grams; grams for 10 dimes. One dime is , or 2.3 grams.

**Coin Stumpers 2**

80 pennies

20 nickels are grams or 100 grams. grams.

pennies.

**Coin Stumpers 3**

20 pennies and 40 dimes

50 grams is , or 20 pennies. grams.

dimes

**Coin Stumpers 4**

20 nickels

20 pennies are grams grams; 18 dimes are grams grams. grams.

nickels.

**Coin Stumpers – Reason Proportionally with Metric Measurements**

**A pile of 100 pennies weighs 250 grams.**

**A nickel weighs twice as much as a penny.**

**What is the weight of a pile of 300 coins, half pennies and half nickels?**

You have already figured out the numbers of grams for a penny and a nickel. Record the number of grams for a dime once you solve problem 1. Then use those weights to solve the other problems on this page and on the page of Extra for Experts.

Show the steps of your solution to each problem.

*Extra for Experts***: Coin Stumpers – Reason Proportionally with Metric Measurements**

Use the coin weights to solve these problems.

Show the steps of your solution to each problem.

**Solutions:**

**Coin Stumpers Extra 1**

$2.20

20 dimes is grams, or 46 grams

grams

pennies

20 dimes is $2.00

20 pennies is $0.20

**Coin Stumpers Extra 2**

200 pennies

nickels/dollar nickels

grams grams of nickels

grams of pennies

pennies

**Coin Stumpers Extra 3**

$.25

30 pennies is , or 75 grams.

20 dimes is , or 46 grams.

grams of nickels

nickels

5 nickels are $.25

**Coin Stumpers Extra 4**

$2.50

15 pennies is , or 37.5 grams.

27 nickels is , or 135 grams.

grams for dimes.

dimes.

15 pennies are $.15, 27 nickels are $1.35, and 10 dimes are $1.00.