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Finding the Fourth Proportional to 91.40, 138.24 and 90.77

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Solution

The fourth proportional to 91.40, 138.24 and 90.77 is: 137.29

Step by Step Solution

  1. Step 1: Write the proportion equation
    91.40 : 138.24 = 90.77 : x
  2. Step 2: Convert to fraction form
    91.40/138.24 = 90.77/x
  3. Step 3: Cross multiply
    91.40x = 138.24 × 90.77
  4. Step 4: Simplify right side
    91.40x = 12,547.35
  5. Step 5: Solve for x
    x = 12,547.35/91.40
  6. Step 6: Final answer
    x = 137.29

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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.