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Finding the Fourth Proportional to 78.17, 117.72 and 74.79

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Solution

The fourth proportional to 78.17, 117.72 and 74.79 is: 112.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.17 : 117.72 = 74.79 : x
  2. Step 2: Convert to fraction form
    78.17/117.72 = 74.79/x
  3. Step 3: Cross multiply
    78.17x = 117.72 × 74.79
  4. Step 4: Simplify right side
    78.17x = 8,804.28
  5. Step 5: Solve for x
    x = 8,804.28/78.17
  6. Step 6: Final answer
    x = 112.64

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Why These Related Problems?

These problems maintain the same ratio (1.51) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.