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Finding the Fourth Proportional to 78.47, 108.18 and 64.64

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Solution

The fourth proportional to 78.47, 108.18 and 64.64 is: 89.10

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.47 : 108.18 = 64.64 : x
  2. Step 2: Convert to fraction form
    78.47/108.18 = 64.64/x
  3. Step 3: Cross multiply
    78.47x = 108.18 × 64.64
  4. Step 4: Simplify right side
    78.47x = 6,992.21
  5. Step 5: Solve for x
    x = 6,992.21/78.47
  6. Step 6: Final answer
    x = 89.10

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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.