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Finding the Fourth Proportional to 421.40, 631.78 and 205.16

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Solution

The fourth proportional to 421.40, 631.78 and 205.16 is: 307.58

Step by Step Solution

  1. Step 1: Write the proportion equation
    421.40 : 631.78 = 205.16 : x
  2. Step 2: Convert to fraction form
    421.40/631.78 = 205.16/x
  3. Step 3: Cross multiply
    421.40x = 631.78 × 205.16
  4. Step 4: Simplify right side
    421.40x = 129,615.98
  5. Step 5: Solve for x
    x = 129,615.98/421.40
  6. Step 6: Final answer
    x = 307.58

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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.