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Finding the Fourth Proportional to 100.90, 151.89 and 72.21

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Solution

The fourth proportional to 100.90, 151.89 and 72.21 is: 108.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    100.90 : 151.89 = 72.21 : x
  2. Step 2: Convert to fraction form
    100.90/151.89 = 72.21/x
  3. Step 3: Cross multiply
    100.90x = 151.89 × 72.21
  4. Step 4: Simplify right side
    100.90x = 10,968.41
  5. Step 5: Solve for x
    x = 10,968.41/100.90
  6. Step 6: Final answer
    x = 108.70

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Why These Related Problems?

These problems maintain the same ratio (1.51) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.