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Finding the Fourth Proportional to 1,113.91, 1,670.61 and 420.65

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Solution

The fourth proportional to 1,113.91, 1,670.61 and 420.65 is: 630.88

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,113.91 : 1,670.61 = 420.65 : x
  2. Step 2: Convert to fraction form
    1,113.91/1,670.61 = 420.65/x
  3. Step 3: Cross multiply
    1,113.91x = 1,670.61 × 420.65
  4. Step 4: Simplify right side
    1,113.91x = 702,739.99
  5. Step 5: Solve for x
    x = 702,739.99/1,113.91
  6. Step 6: Final answer
    x = 630.88

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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.