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Finding the Fourth Proportional to 91.40, 125.30 and 89.78

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Solution

The fourth proportional to 91.40, 125.30 and 89.78 is: 123.08

Step by Step Solution

  1. Step 1: Write the proportion equation
    91.40 : 125.30 = 89.78 : x
  2. Step 2: Convert to fraction form
    91.40/125.30 = 89.78/x
  3. Step 3: Cross multiply
    91.40x = 125.30 × 89.78
  4. Step 4: Simplify right side
    91.40x = 11,249.43
  5. Step 5: Solve for x
    x = 11,249.43/91.40
  6. Step 6: Final answer
    x = 123.08

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Why These Related Problems?

These problems maintain the same ratio (1.37) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.