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Finding the Fourth Proportional to 695.65, 1,042.30 and 420.90

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Solution

The fourth proportional to 695.65, 1,042.30 and 420.90 is: 630.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    695.65 : 1,042.30 = 420.90 : x
  2. Step 2: Convert to fraction form
    695.65/1,042.30 = 420.90/x
  3. Step 3: Cross multiply
    695.65x = 1,042.30 × 420.90
  4. Step 4: Simplify right side
    695.65x = 438,704.07
  5. Step 5: Solve for x
    x = 438,704.07/695.65
  6. Step 6: Final answer
    x = 630.64

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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.