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Finding the Fourth Proportional to 877.80, 1,317.11 and 390.80

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Solution

The fourth proportional to 877.80, 1,317.11 and 390.80 is: 586.37

Step by Step Solution

  1. Step 1: Write the proportion equation
    877.80 : 1,317.11 = 390.80 : x
  2. Step 2: Convert to fraction form
    877.80/1,317.11 = 390.80/x
  3. Step 3: Cross multiply
    877.80x = 1,317.11 × 390.80
  4. Step 4: Simplify right side
    877.80x = 514,718.05
  5. Step 5: Solve for x
    x = 514,718.05/877.80
  6. Step 6: Final answer
    x = 586.37

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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.