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Finding the Fourth Proportional to 491.71, 678.55 and 305.21

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Solution

The fourth proportional to 491.71, 678.55 and 305.21 is: 421.18

Step by Step Solution

  1. Step 1: Write the proportion equation
    491.71 : 678.55 = 305.21 : x
  2. Step 2: Convert to fraction form
    491.71/678.55 = 305.21/x
  3. Step 3: Cross multiply
    491.71x = 678.55 × 305.21
  4. Step 4: Simplify right side
    491.71x = 207,095.33
  5. Step 5: Solve for x
    x = 207,095.33/491.71
  6. Step 6: Final answer
    x = 421.18

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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.