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Finding the Fourth Proportional to 78.31, 117.30 and 64.63

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Solution

The fourth proportional to 78.31, 117.30 and 64.63 is: 96.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.31 : 117.30 = 64.63 : x
  2. Step 2: Convert to fraction form
    78.31/117.30 = 64.63/x
  3. Step 3: Cross multiply
    78.31x = 117.30 × 64.63
  4. Step 4: Simplify right side
    78.31x = 7,581.10
  5. Step 5: Solve for x
    x = 7,581.10/78.31
  6. Step 6: Final answer
    x = 96.81

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.