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Finding the Fourth Proportional to 860.92, 1,291.79 and 428.02

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Solution

The fourth proportional to 860.92, 1,291.79 and 428.02 is: 642.23

Step by Step Solution

  1. Step 1: Write the proportion equation
    860.92 : 1,291.79 = 428.02 : x
  2. Step 2: Convert to fraction form
    860.92/1,291.79 = 428.02/x
  3. Step 3: Cross multiply
    860.92x = 1,291.79 × 428.02
  4. Step 4: Simplify right side
    860.92x = 552,911.96
  5. Step 5: Solve for x
    x = 552,911.96/860.92
  6. Step 6: Final answer
    x = 642.23

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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.