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Finding the Fourth Proportional to 1,287.31, 1,930.95 and 313.40

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Solution

The fourth proportional to 1,287.31, 1,930.95 and 313.40 is: 470.10

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,287.31 : 1,930.95 = 313.40 : x
  2. Step 2: Convert to fraction form
    1,287.31/1,930.95 = 313.40/x
  3. Step 3: Cross multiply
    1,287.31x = 1,930.95 × 313.40
  4. Step 4: Simplify right side
    1,287.31x = 605,158.16
  5. Step 5: Solve for x
    x = 605,158.16/1,287.31
  6. Step 6: Final answer
    x = 470.10

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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.