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Finding the Fourth Proportional to 306.40, 421.86 and 253.30

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Solution

The fourth proportional to 306.40, 421.86 and 253.30 is: 348.75

Step by Step Solution

  1. Step 1: Write the proportion equation
    306.40 : 421.86 = 253.30 : x
  2. Step 2: Convert to fraction form
    306.40/421.86 = 253.30/x
  3. Step 3: Cross multiply
    306.40x = 421.86 × 253.30
  4. Step 4: Simplify right side
    306.40x = 106,857.14
  5. Step 5: Solve for x
    x = 106,857.14/306.40
  6. Step 6: Final answer
    x = 348.75

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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.