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Finding the Fourth Proportional to 91.90, 137.58 and 78.22

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Solution

The fourth proportional to 91.90, 137.58 and 78.22 is: 117.10

Step by Step Solution

  1. Step 1: Write the proportion equation
    91.90 : 137.58 = 78.22 : x
  2. Step 2: Convert to fraction form
    91.90/137.58 = 78.22/x
  3. Step 3: Cross multiply
    91.90x = 137.58 × 78.22
  4. Step 4: Simplify right side
    91.90x = 10,761.51
  5. Step 5: Solve for x
    x = 10,761.51/91.90
  6. Step 6: Final answer
    x = 117.10

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.