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Finding the Fourth Proportional to 831.79, 1,247.91 and 679.15

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Solution

The fourth proportional to 831.79, 1,247.91 and 679.15 is: 1,018.91

Step by Step Solution

  1. Step 1: Write the proportion equation
    831.79 : 1,247.91 = 679.15 : x
  2. Step 2: Convert to fraction form
    831.79/1,247.91 = 679.15/x
  3. Step 3: Cross multiply
    831.79x = 1,247.91 × 679.15
  4. Step 4: Simplify right side
    831.79x = 847,518.08
  5. Step 5: Solve for x
    x = 847,518.08/831.79
  6. Step 6: Final answer
    x = 1,018.91

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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.