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Finding the Fourth Proportional to 78.16, 117.14 and 57.81

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Solution

The fourth proportional to 78.16, 117.14 and 57.81 is: 86.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.16 : 117.14 = 57.81 : x
  2. Step 2: Convert to fraction form
    78.16/117.14 = 57.81/x
  3. Step 3: Cross multiply
    78.16x = 117.14 × 57.81
  4. Step 4: Simplify right side
    78.16x = 6,771.57
  5. Step 5: Solve for x
    x = 6,771.57/78.16
  6. Step 6: Final answer
    x = 86.64

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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.