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Finding the Fourth Proportional to 487.40, 672.80 and 312.75

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Solution

The fourth proportional to 487.40, 672.80 and 312.75 is: 431.72

Step by Step Solution

  1. Step 1: Write the proportion equation
    487.40 : 672.80 = 312.75 : x
  2. Step 2: Convert to fraction form
    487.40/672.80 = 312.75/x
  3. Step 3: Cross multiply
    487.40x = 672.80 × 312.75
  4. Step 4: Simplify right side
    487.40x = 210,416.64
  5. Step 5: Solve for x
    x = 210,416.64/487.40
  6. Step 6: Final answer
    x = 431.72

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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.