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Finding the Fourth Proportional to 78.11, 107.70 and 64.95

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Solution

The fourth proportional to 78.11, 107.70 and 64.95 is: 89.55

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.11 : 107.70 = 64.95 : x
  2. Step 2: Convert to fraction form
    78.11/107.70 = 64.95/x
  3. Step 3: Cross multiply
    78.11x = 107.70 × 64.95
  4. Step 4: Simplify right side
    78.11x = 6,995.07
  5. Step 5: Solve for x
    x = 6,995.07/78.11
  6. Step 6: Final answer
    x = 89.55

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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.