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Finding the Fourth Proportional to 218.78, 328.29 and 90.50

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Solution

The fourth proportional to 218.78, 328.29 and 90.50 is: 135.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    218.78 : 328.29 = 90.50 : x
  2. Step 2: Convert to fraction form
    218.78/328.29 = 90.50/x
  3. Step 3: Cross multiply
    218.78x = 328.29 × 90.50
  4. Step 4: Simplify right side
    218.78x = 29,710.25
  5. Step 5: Solve for x
    x = 29,710.25/218.78
  6. Step 6: Final answer
    x = 135.80

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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.