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Finding the Fourth Proportional to 901.28, 1,243.40 and 665.78

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Solution

The fourth proportional to 901.28, 1,243.40 and 665.78 is: 918.50

Step by Step Solution

  1. Step 1: Write the proportion equation
    901.28 : 1,243.40 = 665.78 : x
  2. Step 2: Convert to fraction form
    901.28/1,243.40 = 665.78/x
  3. Step 3: Cross multiply
    901.28x = 1,243.40 × 665.78
  4. Step 4: Simplify right side
    901.28x = 827,821.31
  5. Step 5: Solve for x
    x = 827,821.31/901.28
  6. Step 6: Final answer
    x = 918.50

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.