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Finding the Fourth Proportional to 90.30, 135.45 and 78.30

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Solution

The fourth proportional to 90.30, 135.45 and 78.30 is: 117.45

Step by Step Solution

  1. Step 1: Write the proportion equation
    90.30 : 135.45 = 78.30 : x
  2. Step 2: Convert to fraction form
    90.30/135.45 = 78.30/x
  3. Step 3: Cross multiply
    90.30x = 135.45 × 78.30
  4. Step 4: Simplify right side
    90.30x = 10,605.74
  5. Step 5: Solve for x
    x = 10,605.74/90.30
  6. Step 6: Final answer
    x = 117.45

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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.