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Finding the Fourth Proportional to 858.60, 1,287.90 and 617.40

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Solution

The fourth proportional to 858.60, 1,287.90 and 617.40 is: 926.10

Step by Step Solution

  1. Step 1: Write the proportion equation
    858.60 : 1,287.90 = 617.40 : x
  2. Step 2: Convert to fraction form
    858.60/1,287.90 = 617.40/x
  3. Step 3: Cross multiply
    858.60x = 1,287.90 × 617.40
  4. Step 4: Simplify right side
    858.60x = 795,149.46
  5. Step 5: Solve for x
    x = 795,149.46/858.60
  6. Step 6: Final answer
    x = 926.10

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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.