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Finding the Fourth Proportional to 695.20, 1,042.80 and 642.40

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Solution

The fourth proportional to 695.20, 1,042.80 and 642.40 is: 963.60

Step by Step Solution

  1. Step 1: Write the proportion equation
    695.20 : 1,042.80 = 642.40 : x
  2. Step 2: Convert to fraction form
    695.20/1,042.80 = 642.40/x
  3. Step 3: Cross multiply
    695.20x = 1,042.80 × 642.40
  4. Step 4: Simplify right side
    695.20x = 669,894.72
  5. Step 5: Solve for x
    x = 669,894.72/695.20
  6. Step 6: Final answer
    x = 963.60

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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.