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Finding the Fourth Proportional to 111.15, 153.36 and 90.39

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Solution

The fourth proportional to 111.15, 153.36 and 90.39 is: 124.72

Step by Step Solution

  1. Step 1: Write the proportion equation
    111.15 : 153.36 = 90.39 : x
  2. Step 2: Convert to fraction form
    111.15/153.36 = 90.39/x
  3. Step 3: Cross multiply
    111.15x = 153.36 × 90.39
  4. Step 4: Simplify right side
    111.15x = 13,862.21
  5. Step 5: Solve for x
    x = 13,862.21/111.15
  6. Step 6: Final answer
    x = 124.72

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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.