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Finding the Fourth Proportional to 1,281.16, 1,921.14 and 812.76

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Solution

The fourth proportional to 1,281.16, 1,921.14 and 812.76 is: 1,218.76

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,281.16 : 1,921.14 = 812.76 : x
  2. Step 2: Convert to fraction form
    1,281.16/1,921.14 = 812.76/x
  3. Step 3: Cross multiply
    1,281.16x = 1,921.14 × 812.76
  4. Step 4: Simplify right side
    1,281.16x = 1,561,425.75
  5. Step 5: Solve for x
    x = 1,561,425.75/1,281.16
  6. Step 6: Final answer
    x = 1,218.76

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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.