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Finding the Fourth Proportional to 78.18, 107.90 and 64.34

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Solution

The fourth proportional to 78.18, 107.90 and 64.34 is: 88.79

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.18 : 107.90 = 64.34 : x
  2. Step 2: Convert to fraction form
    78.18/107.90 = 64.34/x
  3. Step 3: Cross multiply
    78.18x = 107.90 × 64.34
  4. Step 4: Simplify right side
    78.18x = 6,941.42
  5. Step 5: Solve for x
    x = 6,941.42/78.18
  6. Step 6: Final answer
    x = 88.79

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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.