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Finding the Fourth Proportional to 78.56, 108.14 and 64.69

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Solution

The fourth proportional to 78.56, 108.14 and 64.69 is: 89.05

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.56 : 108.14 = 64.69 : x
  2. Step 2: Convert to fraction form
    78.56/108.14 = 64.69/x
  3. Step 3: Cross multiply
    78.56x = 108.14 × 64.69
  4. Step 4: Simplify right side
    78.56x = 6,995.58
  5. Step 5: Solve for x
    x = 6,995.58/78.56
  6. Step 6: Final answer
    x = 89.05

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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.