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Finding the Fourth Proportional to 57.36, 78.90 and 47.40

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Solution

The fourth proportional to 57.36, 78.90 and 47.40 is: 65.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    57.36 : 78.90 = 47.40 : x
  2. Step 2: Convert to fraction form
    57.36/78.90 = 47.40/x
  3. Step 3: Cross multiply
    57.36x = 78.90 × 47.40
  4. Step 4: Simplify right side
    57.36x = 3,739.86
  5. Step 5: Solve for x
    x = 3,739.86/57.36
  6. Step 6: Final answer
    x = 65.20

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.