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Finding the Fourth Proportional to 714.20, 985.61 and 399.45

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Solution

The fourth proportional to 714.20, 985.61 and 399.45 is: 551.25

Step by Step Solution

  1. Step 1: Write the proportion equation
    714.20 : 985.61 = 399.45 : x
  2. Step 2: Convert to fraction form
    714.20/985.61 = 399.45/x
  3. Step 3: Cross multiply
    714.20x = 985.61 × 399.45
  4. Step 4: Simplify right side
    714.20x = 393,701.91
  5. Step 5: Solve for x
    x = 393,701.91/714.20
  6. Step 6: Final answer
    x = 551.25

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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.