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Finding the Fourth Proportional to 985.21, 1,359.86 and 631.10

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Solution

The fourth proportional to 985.21, 1,359.86 and 631.10 is: 871.09

Step by Step Solution

  1. Step 1: Write the proportion equation
    985.21 : 1,359.86 = 631.10 : x
  2. Step 2: Convert to fraction form
    985.21/1,359.86 = 631.10/x
  3. Step 3: Cross multiply
    985.21x = 1,359.86 × 631.10
  4. Step 4: Simplify right side
    985.21x = 858,207.89
  5. Step 5: Solve for x
    x = 858,207.89/985.21
  6. Step 6: Final answer
    x = 871.09

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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.