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Finding the Fourth Proportional to 78.85, 117.64 and 71.16

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Solution

The fourth proportional to 78.85, 117.64 and 71.16 is: 106.17

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.85 : 117.64 = 71.16 : x
  2. Step 2: Convert to fraction form
    78.85/117.64 = 71.16/x
  3. Step 3: Cross multiply
    78.85x = 117.64 × 71.16
  4. Step 4: Simplify right side
    78.85x = 8,371.26
  5. Step 5: Solve for x
    x = 8,371.26/78.85
  6. Step 6: Final answer
    x = 106.17

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.