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Finding the Fourth Proportional to 285.48, 428 and 139.14

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Solution

The fourth proportional to 285.48, 428 and 139.14 is: 208.60

Step by Step Solution

  1. Step 1: Write the proportion equation
    285.48 : 428 = 139.14 : x
  2. Step 2: Convert to fraction form
    285.48/428 = 139.14/x
  3. Step 3: Cross multiply
    285.48x = 428 × 139.14
  4. Step 4: Simplify right side
    285.48x = 59,551.92
  5. Step 5: Solve for x
    x = 59,551.92/285.48
  6. Step 6: Final answer
    x = 208.60

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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.