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Finding the Fourth Proportional to 877.50, 1,315.89 and 390.87

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Solution

The fourth proportional to 877.50, 1,315.89 and 390.87 is: 586.14

Step by Step Solution

  1. Step 1: Write the proportion equation
    877.50 : 1,315.89 = 390.87 : x
  2. Step 2: Convert to fraction form
    877.50/1,315.89 = 390.87/x
  3. Step 3: Cross multiply
    877.50x = 1,315.89 × 390.87
  4. Step 4: Simplify right side
    877.50x = 514,341.92
  5. Step 5: Solve for x
    x = 514,341.92/877.50
  6. Step 6: Final answer
    x = 586.14

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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.