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Finding the Fourth Proportional to 307.20, 422.88 and 290.40

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Solution

The fourth proportional to 307.20, 422.88 and 290.40 is: 399.75

Step by Step Solution

  1. Step 1: Write the proportion equation
    307.20 : 422.88 = 290.40 : x
  2. Step 2: Convert to fraction form
    307.20/422.88 = 290.40/x
  3. Step 3: Cross multiply
    307.20x = 422.88 × 290.40
  4. Step 4: Simplify right side
    307.20x = 122,804.35
  5. Step 5: Solve for x
    x = 122,804.35/307.20
  6. Step 6: Final answer
    x = 399.75

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.