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Finding the Fourth Proportional to 120.50, 180.78 and 77.45

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Solution

The fourth proportional to 120.50, 180.78 and 77.45 is: 116.19

Step by Step Solution

  1. Step 1: Write the proportion equation
    120.50 : 180.78 = 77.45 : x
  2. Step 2: Convert to fraction form
    120.50/180.78 = 77.45/x
  3. Step 3: Cross multiply
    120.50x = 180.78 × 77.45
  4. Step 4: Simplify right side
    120.50x = 14,000.51
  5. Step 5: Solve for x
    x = 14,000.51/120.50
  6. Step 6: Final answer
    x = 116.19

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.