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Finding the Fourth Proportional to 831.60, 1,247.40 and 612.90

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Solution

The fourth proportional to 831.60, 1,247.40 and 612.90 is: 919.35

Step by Step Solution

  1. Step 1: Write the proportion equation
    831.60 : 1,247.40 = 612.90 : x
  2. Step 2: Convert to fraction form
    831.60/1,247.40 = 612.90/x
  3. Step 3: Cross multiply
    831.60x = 1,247.40 × 612.90
  4. Step 4: Simplify right side
    831.60x = 764,531.46
  5. Step 5: Solve for x
    x = 764,531.46/831.60
  6. Step 6: Final answer
    x = 919.35

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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.