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Finding the Fourth Proportional to 312.09, 430.70 and 172.20

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Solution

The fourth proportional to 312.09, 430.70 and 172.20 is: 237.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    312.09 : 430.70 = 172.20 : x
  2. Step 2: Convert to fraction form
    312.09/430.70 = 172.20/x
  3. Step 3: Cross multiply
    312.09x = 430.70 × 172.20
  4. Step 4: Simplify right side
    312.09x = 74,165.68
  5. Step 5: Solve for x
    x = 74,165.68/312.09
  6. Step 6: Final answer
    x = 237.64

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.