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Finding the Fourth Proportional to 78.42, 108.26 and 64.64

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Solution

The fourth proportional to 78.42, 108.26 and 64.64 is: 89.24

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.42 : 108.26 = 64.64 : x
  2. Step 2: Convert to fraction form
    78.42/108.26 = 64.64/x
  3. Step 3: Cross multiply
    78.42x = 108.26 × 64.64
  4. Step 4: Simplify right side
    78.42x = 6,997.93
  5. Step 5: Solve for x
    x = 6,997.93/78.42
  6. Step 6: Final answer
    x = 89.24

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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.