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Finding the Fourth Proportional to 1,320.24, 1,978.47 and 831.90

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Solution

The fourth proportional to 1,320.24, 1,978.47 and 831.90 is: 1,246.66

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,320.24 : 1,978.47 = 831.90 : x
  2. Step 2: Convert to fraction form
    1,320.24/1,978.47 = 831.90/x
  3. Step 3: Cross multiply
    1,320.24x = 1,978.47 × 831.90
  4. Step 4: Simplify right side
    1,320.24x = 1,645,889.19
  5. Step 5: Solve for x
    x = 1,645,889.19/1,320.24
  6. Step 6: Final answer
    x = 1,246.66

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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.