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Finding the Fourth Proportional to 78.16, 117.32 and 66.84

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Solution

The fourth proportional to 78.16, 117.32 and 66.84 is: 100.33

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.16 : 117.32 = 66.84 : x
  2. Step 2: Convert to fraction form
    78.16/117.32 = 66.84/x
  3. Step 3: Cross multiply
    78.16x = 117.32 × 66.84
  4. Step 4: Simplify right side
    78.16x = 7,841.67
  5. Step 5: Solve for x
    x = 7,841.67/78.16
  6. Step 6: Final answer
    x = 100.33

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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.