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Finding the Fourth Proportional to 78.50, 108.43 and 72

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Solution

The fourth proportional to 78.50, 108.43 and 72 is: 99.45

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.50 : 108.43 = 72 : x
  2. Step 2: Convert to fraction form
    78.50/108.43 = 72/x
  3. Step 3: Cross multiply
    78.50x = 108.43 × 72
  4. Step 4: Simplify right side
    78.50x = 7,806.78
  5. Step 5: Solve for x
    x = 7,806.78/78.50
  6. Step 6: Final answer
    x = 99.45

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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.