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Finding the Fourth Proportional to 90.74, 135.51 and 78.59

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Solution

The fourth proportional to 90.74, 135.51 and 78.59 is: 117.37

Step by Step Solution

  1. Step 1: Write the proportion equation
    90.74 : 135.51 = 78.59 : x
  2. Step 2: Convert to fraction form
    90.74/135.51 = 78.59/x
  3. Step 3: Cross multiply
    90.74x = 135.51 × 78.59
  4. Step 4: Simplify right side
    90.74x = 10,649.35
  5. Step 5: Solve for x
    x = 10,649.35/90.74
  6. Step 6: Final answer
    x = 117.37

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.