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Finding the Fourth Proportional to 421.84, 627.71 and 420.40

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Solution

The fourth proportional to 421.84, 627.71 and 420.40 is: 625.57

Step by Step Solution

  1. Step 1: Write the proportion equation
    421.84 : 627.71 = 420.40 : x
  2. Step 2: Convert to fraction form
    421.84/627.71 = 420.40/x
  3. Step 3: Cross multiply
    421.84x = 627.71 × 420.40
  4. Step 4: Simplify right side
    421.84x = 263,889.28
  5. Step 5: Solve for x
    x = 263,889.28/421.84
  6. Step 6: Final answer
    x = 625.57

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.