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Finding the Fourth Proportional to 861.51, 1,188.90 and 512.40

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Solution

The fourth proportional to 861.51, 1,188.90 and 512.40 is: 707.12

Step by Step Solution

  1. Step 1: Write the proportion equation
    861.51 : 1,188.90 = 512.40 : x
  2. Step 2: Convert to fraction form
    861.51/1,188.90 = 512.40/x
  3. Step 3: Cross multiply
    861.51x = 1,188.90 × 512.40
  4. Step 4: Simplify right side
    861.51x = 609,192.36
  5. Step 5: Solve for x
    x = 609,192.36/861.51
  6. Step 6: Final answer
    x = 707.12

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.