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Finding the Fourth Proportional to 78.88, 108.26 and 72.40

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Solution

The fourth proportional to 78.88, 108.26 and 72.40 is: 99.37

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.88 : 108.26 = 72.40 : x
  2. Step 2: Convert to fraction form
    78.88/108.26 = 72.40/x
  3. Step 3: Cross multiply
    78.88x = 108.26 × 72.40
  4. Step 4: Simplify right side
    78.88x = 7,838.02
  5. Step 5: Solve for x
    x = 7,838.02/78.88
  6. Step 6: Final answer
    x = 99.37

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Why These Related Problems?

These problems maintain the same ratio (1.37) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.