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Finding the Fourth Proportional to 831.51, 1,247.25 and 215.21

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Solution

The fourth proportional to 831.51, 1,247.25 and 215.21 is: 322.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    831.51 : 1,247.25 = 215.21 : x
  2. Step 2: Convert to fraction form
    831.51/1,247.25 = 215.21/x
  3. Step 3: Cross multiply
    831.51x = 1,247.25 × 215.21
  4. Step 4: Simplify right side
    831.51x = 268,422.98
  5. Step 5: Solve for x
    x = 268,422.98/831.51
  6. Step 6: Final answer
    x = 322.81

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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.