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Finding the Fourth Proportional to 861.74, 1,290.80 and 715.13

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Solution

The fourth proportional to 861.74, 1,290.80 and 715.13 is: 1,071.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    861.74 : 1,290.80 = 715.13 : x
  2. Step 2: Convert to fraction form
    861.74/1,290.80 = 715.13/x
  3. Step 3: Cross multiply
    861.74x = 1,290.80 × 715.13
  4. Step 4: Simplify right side
    861.74x = 923,094.82
  5. Step 5: Solve for x
    x = 923,094.82/861.74
  6. Step 6: Final answer
    x = 1,071.20

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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.