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Finding the Fourth Proportional to 84.81, 126.51 and 78

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Solution

The fourth proportional to 84.81, 126.51 and 78 is: 116.35

Step by Step Solution

  1. Step 1: Write the proportion equation
    84.81 : 126.51 = 78 : x
  2. Step 2: Convert to fraction form
    84.81/126.51 = 78/x
  3. Step 3: Cross multiply
    84.81x = 126.51 × 78
  4. Step 4: Simplify right side
    84.81x = 9,867.78
  5. Step 5: Solve for x
    x = 9,867.78/84.81
  6. Step 6: Final answer
    x = 116.35

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.