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Finding the Fourth Proportional to 1,031.88, 1,423.98 and 639

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Solution

The fourth proportional to 1,031.88, 1,423.98 and 639 is: 881.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,031.88 : 1,423.98 = 639 : x
  2. Step 2: Convert to fraction form
    1,031.88/1,423.98 = 639/x
  3. Step 3: Cross multiply
    1,031.88x = 1,423.98 × 639
  4. Step 4: Simplify right side
    1,031.88x = 909,923.22
  5. Step 5: Solve for x
    x = 909,923.22/1,031.88
  6. Step 6: Final answer
    x = 881.81

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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.