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Finding the Fourth Proportional to 78.40, 116.79 and 74.47

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Solution

The fourth proportional to 78.40, 116.79 and 74.47 is: 110.94

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.40 : 116.79 = 74.47 : x
  2. Step 2: Convert to fraction form
    78.40/116.79 = 74.47/x
  3. Step 3: Cross multiply
    78.40x = 116.79 × 74.47
  4. Step 4: Simplify right side
    78.40x = 8,697.35
  5. Step 5: Solve for x
    x = 8,697.35/78.40
  6. Step 6: Final answer
    x = 110.94

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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.