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Finding the Fourth Proportional to 309.40, 426.64 and 211.20

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Solution

The fourth proportional to 309.40, 426.64 and 211.20 is: 291.23

Step by Step Solution

  1. Step 1: Write the proportion equation
    309.40 : 426.64 = 211.20 : x
  2. Step 2: Convert to fraction form
    309.40/426.64 = 211.20/x
  3. Step 3: Cross multiply
    309.40x = 426.64 × 211.20
  4. Step 4: Simplify right side
    309.40x = 90,106.37
  5. Step 5: Solve for x
    x = 90,106.37/309.40
  6. Step 6: Final answer
    x = 291.23

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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.