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Finding the Fourth Proportional to 316.40, 474.20 and 280.40

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Solution

The fourth proportional to 316.40, 474.20 and 280.40 is: 420.25

Step by Step Solution

  1. Step 1: Write the proportion equation
    316.40 : 474.20 = 280.40 : x
  2. Step 2: Convert to fraction form
    316.40/474.20 = 280.40/x
  3. Step 3: Cross multiply
    316.40x = 474.20 × 280.40
  4. Step 4: Simplify right side
    316.40x = 132,965.68
  5. Step 5: Solve for x
    x = 132,965.68/316.40
  6. Step 6: Final answer
    x = 420.25

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.