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Finding the Fourth Proportional to 861.51, 1,290.55 and 398.65

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Solution

The fourth proportional to 861.51, 1,290.55 and 398.65 is: 597.18

Step by Step Solution

  1. Step 1: Write the proportion equation
    861.51 : 1,290.55 = 398.65 : x
  2. Step 2: Convert to fraction form
    861.51/1,290.55 = 398.65/x
  3. Step 3: Cross multiply
    861.51x = 1,290.55 × 398.65
  4. Step 4: Simplify right side
    861.51x = 514,477.76
  5. Step 5: Solve for x
    x = 514,477.76/861.51
  6. Step 6: Final answer
    x = 597.18

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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.