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Finding the Fourth Proportional to 78.99, 108.99 and 57.21

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Solution

The fourth proportional to 78.99, 108.99 and 57.21 is: 78.94

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.99 : 108.99 = 57.21 : x
  2. Step 2: Convert to fraction form
    78.99/108.99 = 57.21/x
  3. Step 3: Cross multiply
    78.99x = 108.99 × 57.21
  4. Step 4: Simplify right side
    78.99x = 6,235.32
  5. Step 5: Solve for x
    x = 6,235.32/78.99
  6. Step 6: Final answer
    x = 78.94

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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.