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Finding the Fourth Proportional to 78.39, 108.21 and 50.76

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Solution

The fourth proportional to 78.39, 108.21 and 50.76 is: 70.07

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.39 : 108.21 = 50.76 : x
  2. Step 2: Convert to fraction form
    78.39/108.21 = 50.76/x
  3. Step 3: Cross multiply
    78.39x = 108.21 × 50.76
  4. Step 4: Simplify right side
    78.39x = 5,492.74
  5. Step 5: Solve for x
    x = 5,492.74/78.39
  6. Step 6: Final answer
    x = 70.07

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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.