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Finding the Fourth Proportional to 91.45, 137.86 and 90.64

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Solution

The fourth proportional to 91.45, 137.86 and 90.64 is: 136.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    91.45 : 137.86 = 90.64 : x
  2. Step 2: Convert to fraction form
    91.45/137.86 = 90.64/x
  3. Step 3: Cross multiply
    91.45x = 137.86 × 90.64
  4. Step 4: Simplify right side
    91.45x = 12,495.63
  5. Step 5: Solve for x
    x = 12,495.63/91.45
  6. Step 6: Final answer
    x = 136.64

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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.