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Finding the Fourth Proportional to 78.60, 117.86 and 61.50

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Solution

The fourth proportional to 78.60, 117.86 and 61.50 is: 92.22

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.60 : 117.86 = 61.50 : x
  2. Step 2: Convert to fraction form
    78.60/117.86 = 61.50/x
  3. Step 3: Cross multiply
    78.60x = 117.86 × 61.50
  4. Step 4: Simplify right side
    78.60x = 7,248.39
  5. Step 5: Solve for x
    x = 7,248.39/78.60
  6. Step 6: Final answer
    x = 92.22

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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.