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Finding the Fourth Proportional to 831.25, 1,245.79 and 420.45

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Solution

The fourth proportional to 831.25, 1,245.79 and 420.45 is: 630.13

Step by Step Solution

  1. Step 1: Write the proportion equation
    831.25 : 1,245.79 = 420.45 : x
  2. Step 2: Convert to fraction form
    831.25/1,245.79 = 420.45/x
  3. Step 3: Cross multiply
    831.25x = 1,245.79 × 420.45
  4. Step 4: Simplify right side
    831.25x = 523,792.41
  5. Step 5: Solve for x
    x = 523,792.41/831.25
  6. Step 6: Final answer
    x = 630.13

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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.