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Finding the Fourth Proportional to 121.32, 167.40 and 99.72

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Solution

The fourth proportional to 121.32, 167.40 and 99.72 is: 137.60

Step by Step Solution

  1. Step 1: Write the proportion equation
    121.32 : 167.40 = 99.72 : x
  2. Step 2: Convert to fraction form
    121.32/167.40 = 99.72/x
  3. Step 3: Cross multiply
    121.32x = 167.40 × 99.72
  4. Step 4: Simplify right side
    121.32x = 16,693.13
  5. Step 5: Solve for x
    x = 16,693.13/121.32
  6. Step 6: Final answer
    x = 137.60

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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.