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Finding the Fourth Proportional to 681.40, 1,021.60 and 218.90

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Solution

The fourth proportional to 681.40, 1,021.60 and 218.90 is: 328.19

Step by Step Solution

  1. Step 1: Write the proportion equation
    681.40 : 1,021.60 = 218.90 : x
  2. Step 2: Convert to fraction form
    681.40/1,021.60 = 218.90/x
  3. Step 3: Cross multiply
    681.40x = 1,021.60 × 218.90
  4. Step 4: Simplify right side
    681.40x = 223,628.24
  5. Step 5: Solve for x
    x = 223,628.24/681.40
  6. Step 6: Final answer
    x = 328.19

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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.