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Finding the Fourth Proportional to 102.12, 153.75 and 91.80

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Solution

The fourth proportional to 102.12, 153.75 and 91.80 is: 138.21

Step by Step Solution

  1. Step 1: Write the proportion equation
    102.12 : 153.75 = 91.80 : x
  2. Step 2: Convert to fraction form
    102.12/153.75 = 91.80/x
  3. Step 3: Cross multiply
    102.12x = 153.75 × 91.80
  4. Step 4: Simplify right side
    102.12x = 14,114.25
  5. Step 5: Solve for x
    x = 14,114.25/102.12
  6. Step 6: Final answer
    x = 138.21

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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.