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Finding the Fourth Proportional to 74.80, 103.20 and 66.40

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Solution

The fourth proportional to 74.80, 103.20 and 66.40 is: 91.61

Step by Step Solution

  1. Step 1: Write the proportion equation
    74.80 : 103.20 = 66.40 : x
  2. Step 2: Convert to fraction form
    74.80/103.20 = 66.40/x
  3. Step 3: Cross multiply
    74.80x = 103.20 × 66.40
  4. Step 4: Simplify right side
    74.80x = 6,852.48
  5. Step 5: Solve for x
    x = 6,852.48/74.80
  6. Step 6: Final answer
    x = 91.61

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.