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Finding the Fourth Proportional to 420.48, 580 and 280.32

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Solution

The fourth proportional to 420.48, 580 and 280.32 is: 386.67

Step by Step Solution

  1. Step 1: Write the proportion equation
    420.48 : 580 = 280.32 : x
  2. Step 2: Convert to fraction form
    420.48/580 = 280.32/x
  3. Step 3: Cross multiply
    420.48x = 580 × 280.32
  4. Step 4: Simplify right side
    420.48x = 162,585.60
  5. Step 5: Solve for x
    x = 162,585.60/420.48
  6. Step 6: Final answer
    x = 386.67

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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.