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Finding the Fourth Proportional to 78.51, 117.14 and 74.87

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Solution

The fourth proportional to 78.51, 117.14 and 74.87 is: 111.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.51 : 117.14 = 74.87 : x
  2. Step 2: Convert to fraction form
    78.51/117.14 = 74.87/x
  3. Step 3: Cross multiply
    78.51x = 117.14 × 74.87
  4. Step 4: Simplify right side
    78.51x = 8,769.31
  5. Step 5: Solve for x
    x = 8,769.31/78.51
  6. Step 6: Final answer
    x = 111.70

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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.