Math Problem Statement

There are some nickels, dimes, and quarters in a large piggy bank. For every 2 nickels there are 3 dimes. For every 2 dimes there are 5 quarters. There are 500 coins total. How many nickels are there, how many dimes are there, how many quarters are there, and what is the total value of the coins in the piggy bank?

Solution

Let's break down this problem step by step.

Given:

  1. Relationship between coins:

    • For every 2 nickels, there are 3 dimes.
    • For every 2 dimes, there are 5 quarters.
  2. Total coins: 500 coins.

Let's use these relationships to set up equations.

Step 1: Set Up Variables

Let:

  • NN = Number of nickels
  • DD = Number of dimes
  • QQ = Number of quarters

Step 2: Set Up Ratios Based on Given Relationships

  1. Nickel to Dime Ratio: For every 2 nickels, there are 3 dimes. This gives us: ND=23N=23D\frac{N}{D} = \frac{2}{3} \Rightarrow N = \frac{2}{3}D

  2. Dime to Quarter Ratio: For every 2 dimes, there are 5 quarters. This gives us: DQ=25D=25Q\frac{D}{Q} = \frac{2}{5} \Rightarrow D = \frac{2}{5}Q

Step 3: Express All Variables in Terms of Quarters

From the second equation, we have: D=25QD = \frac{2}{5}Q Now, substitute DD in the equation for NN: N=23×25Q=415QN = \frac{2}{3} \times \frac{2}{5}Q = \frac{4}{15}Q

Step 4: Set Up the Total Coin Equation

Since the total number of coins is 500, we can write: N+D+Q=500N + D + Q = 500 Substitute NN and DD in terms of QQ: 415Q+25Q+Q=500\frac{4}{15}Q + \frac{2}{5}Q + Q = 500

Step 5: Simplify the Equation

To combine terms, find a common denominator. The denominators are 15 and 5, so convert them all to a denominator of 15: 415Q+615Q+1515Q=500\frac{4}{15}Q + \frac{6}{15}Q + \frac{15}{15}Q = 500 Combine the terms: 2515Q=500\frac{25}{15}Q = 500 Simplify the fraction: 53Q=500\frac{5}{3}Q = 500 Multiply both sides by 3 to solve for QQ: 5Q=15005Q = 1500 Now, divide by 5: Q=300Q = 300

Step 6: Find DD and NN

Now that we know Q=300Q = 300, substitute back to find DD and NN:

  1. Dimes: D=25Q=25×300=120D = \frac{2}{5}Q = \frac{2}{5} \times 300 = 120
  2. Nickels: N=415Q=415×300=80N = \frac{4}{15}Q = \frac{4}{15} \times 300 = 80

Step 7: Calculate the Total Value

  • Nickels: 80 nickels at $0.05 each = 80×0.05=480 \times 0.05 = 4 dollars
  • Dimes: 120 dimes at $0.10 each = 120×0.10=12120 \times 0.10 = 12 dollars
  • Quarters: 300 quarters at $0.25 each = 300×0.25=75300 \times 0.25 = 75 dollars

Total value: 4+12+75=91 dollars4 + 12 + 75 = 91 \text{ dollars}

Final Answers

  • Nickels: 80
  • Dimes: 120
  • Quarters: 300
  • Total value: $91

Would you like a detailed breakdown of any specific step, or do you have further questions?

Here are five related questions to expand on this problem:

  1. How would the total coin count change if there were an additional type of coin?
  2. What if the ratio of nickels to dimes changed to 1:1? How would that affect the distribution?
  3. How would the total value change if each coin type had a different value?
  4. What is the algebraic approach to solving the problem without substituting for quarters first?
  5. Can we use matrix methods to solve systems of equations for more complex coin problems?

Tip: For ratio-based problems, always try expressing all variables in terms of a single variable to simplify calculations.

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Math Problem Analysis

Mathematical Concepts

Ratios and Proportions
Algebra
Systems of Equations

Formulas

Ratio relationships: N/D = 2/3 and D/Q = 2/5
Total coins equation: N + D + Q = 500

Theorems

Basic proportional reasoning and algebraic manipulation

Suitable Grade Level

Grades 7-9