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Finding the Fourth Proportional to 78.56, 117 and 78.10

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Solution

The fourth proportional to 78.56, 117 and 78.10 is: 116.31

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.56 : 117 = 78.10 : x
  2. Step 2: Convert to fraction form
    78.56/117 = 78.10/x
  3. Step 3: Cross multiply
    78.56x = 117 × 78.10
  4. Step 4: Simplify right side
    78.56x = 9,137.70
  5. Step 5: Solve for x
    x = 9,137.70/78.56
  6. Step 6: Final answer
    x = 116.31

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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.