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Finding the Fourth Proportional to 695.40, 1,042.20 and 421.20

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Solution

The fourth proportional to 695.40, 1,042.20 and 421.20 is: 631.25

Step by Step Solution

  1. Step 1: Write the proportion equation
    695.40 : 1,042.20 = 421.20 : x
  2. Step 2: Convert to fraction form
    695.40/1,042.20 = 421.20/x
  3. Step 3: Cross multiply
    695.40x = 1,042.20 × 421.20
  4. Step 4: Simplify right side
    695.40x = 438,974.64
  5. Step 5: Solve for x
    x = 438,974.64/695.40
  6. Step 6: Final answer
    x = 631.25

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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.