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Finding the Fourth Proportional to 431.40, 647.21 and 212.00

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Solution

The fourth proportional to 431.40, 647.21 and 212.00 is: 318.06

Step by Step Solution

  1. Step 1: Write the proportion equation
    431.40 : 647.21 = 212.00 : x
  2. Step 2: Convert to fraction form
    431.40/647.21 = 212.00/x
  3. Step 3: Cross multiply
    431.40x = 647.21 × 212.00
  4. Step 4: Simplify right side
    431.40x = 137,210.67
  5. Step 5: Solve for x
    x = 137,210.67/431.40
  6. Step 6: Final answer
    x = 318.06

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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.