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Finding the Fourth Proportional to 78.42, 108.21 and 65.46

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Solution

The fourth proportional to 78.42, 108.21 and 65.46 is: 90.33

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.42 : 108.21 = 65.46 : x
  2. Step 2: Convert to fraction form
    78.42/108.21 = 65.46/x
  3. Step 3: Cross multiply
    78.42x = 108.21 × 65.46
  4. Step 4: Simplify right side
    78.42x = 7,083.43
  5. Step 5: Solve for x
    x = 7,083.43/78.42
  6. Step 6: Final answer
    x = 90.33

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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.