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Finding the Fourth Proportional to 121.65, 167.51 and 99.78

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Solution

The fourth proportional to 121.65, 167.51 and 99.78 is: 137.39

Step by Step Solution

  1. Step 1: Write the proportion equation
    121.65 : 167.51 = 99.78 : x
  2. Step 2: Convert to fraction form
    121.65/167.51 = 99.78/x
  3. Step 3: Cross multiply
    121.65x = 167.51 × 99.78
  4. Step 4: Simplify right side
    121.65x = 16,713.65
  5. Step 5: Solve for x
    x = 16,713.65/121.65
  6. Step 6: Final answer
    x = 137.39

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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.