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Finding the Fourth Proportional to 82.50, 122.90 and 78.63

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Solution

The fourth proportional to 82.50, 122.90 and 78.63 is: 117.13

Step by Step Solution

  1. Step 1: Write the proportion equation
    82.50 : 122.90 = 78.63 : x
  2. Step 2: Convert to fraction form
    82.50/122.90 = 78.63/x
  3. Step 3: Cross multiply
    82.50x = 122.90 × 78.63
  4. Step 4: Simplify right side
    82.50x = 9,663.63
  5. Step 5: Solve for x
    x = 9,663.63/82.50
  6. Step 6: Final answer
    x = 117.13

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.