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Finding the Fourth Proportional to 78.39, 117.59 and 30.31

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Solution

The fourth proportional to 78.39, 117.59 and 30.31 is: 45.47

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.39 : 117.59 = 30.31 : x
  2. Step 2: Convert to fraction form
    78.39/117.59 = 30.31/x
  3. Step 3: Cross multiply
    78.39x = 117.59 × 30.31
  4. Step 4: Simplify right side
    78.39x = 3,564.15
  5. Step 5: Solve for x
    x = 3,564.15/78.39
  6. Step 6: Final answer
    x = 45.47

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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.