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Finding the Fourth Proportional to 831.69, 1,247.13 and 421.02

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Solution

The fourth proportional to 831.69, 1,247.13 and 421.02 is: 631.32

Step by Step Solution

  1. Step 1: Write the proportion equation
    831.69 : 1,247.13 = 421.02 : x
  2. Step 2: Convert to fraction form
    831.69/1,247.13 = 421.02/x
  3. Step 3: Cross multiply
    831.69x = 1,247.13 × 421.02
  4. Step 4: Simplify right side
    831.69x = 525,066.67
  5. Step 5: Solve for x
    x = 525,066.67/831.69
  6. Step 6: Final answer
    x = 631.32

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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.