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Finding the Fourth Proportional to 78.10, 107.80 and 49

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Solution

The fourth proportional to 78.10, 107.80 and 49 is: 67.63

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.10 : 107.80 = 49 : x
  2. Step 2: Convert to fraction form
    78.10/107.80 = 49/x
  3. Step 3: Cross multiply
    78.10x = 107.80 × 49
  4. Step 4: Simplify right side
    78.10x = 5,282.20
  5. Step 5: Solve for x
    x = 5,282.20/78.10
  6. Step 6: Final answer
    x = 67.63

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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.