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Finding the Fourth Proportional to 831.78, 1,248.18 and 312.15

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Solution

The fourth proportional to 831.78, 1,248.18 and 312.15 is: 468.42

Step by Step Solution

  1. Step 1: Write the proportion equation
    831.78 : 1,248.18 = 312.15 : x
  2. Step 2: Convert to fraction form
    831.78/1,248.18 = 312.15/x
  3. Step 3: Cross multiply
    831.78x = 1,248.18 × 312.15
  4. Step 4: Simplify right side
    831.78x = 389,619.39
  5. Step 5: Solve for x
    x = 389,619.39/831.78
  6. Step 6: Final answer
    x = 468.42

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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.