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Finding the Fourth Proportional to 858.60, 1,288.50 and 642.60

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Solution

The fourth proportional to 858.60, 1,288.50 and 642.60 is: 964.35

Step by Step Solution

  1. Step 1: Write the proportion equation
    858.60 : 1,288.50 = 642.60 : x
  2. Step 2: Convert to fraction form
    858.60/1,288.50 = 642.60/x
  3. Step 3: Cross multiply
    858.60x = 1,288.50 × 642.60
  4. Step 4: Simplify right side
    858.60x = 827,990.10
  5. Step 5: Solve for x
    x = 827,990.10/858.60
  6. Step 6: Final answer
    x = 964.35

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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.