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Finding the Fourth Proportional to 869.90, 1,200.74 and 515.80

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Solution

The fourth proportional to 869.90, 1,200.74 and 515.80 is: 711.97

Step by Step Solution

  1. Step 1: Write the proportion equation
    869.90 : 1,200.74 = 515.80 : x
  2. Step 2: Convert to fraction form
    869.90/1,200.74 = 515.80/x
  3. Step 3: Cross multiply
    869.90x = 1,200.74 × 515.80
  4. Step 4: Simplify right side
    869.90x = 619,341.69
  5. Step 5: Solve for x
    x = 619,341.69/869.90
  6. Step 6: Final answer
    x = 711.97

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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.