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Finding the Fourth Proportional to 1,287.75, 1,931.62 and 313.86

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Solution

The fourth proportional to 1,287.75, 1,931.62 and 313.86 is: 470.79

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,287.75 : 1,931.62 = 313.86 : x
  2. Step 2: Convert to fraction form
    1,287.75/1,931.62 = 313.86/x
  3. Step 3: Cross multiply
    1,287.75x = 1,931.62 × 313.86
  4. Step 4: Simplify right side
    1,287.75x = 606,258.25
  5. Step 5: Solve for x
    x = 606,258.25/1,287.75
  6. Step 6: Final answer
    x = 470.79

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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.