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Finding the Fourth Proportional to 1,274.64, 1,909.78 and 688.20

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Solution

The fourth proportional to 1,274.64, 1,909.78 and 688.20 is: 1,031.12

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,274.64 : 1,909.78 = 688.20 : x
  2. Step 2: Convert to fraction form
    1,274.64/1,909.78 = 688.20/x
  3. Step 3: Cross multiply
    1,274.64x = 1,909.78 × 688.20
  4. Step 4: Simplify right side
    1,274.64x = 1,314,301.71
  5. Step 5: Solve for x
    x = 1,314,301.71/1,274.64
  6. Step 6: Final answer
    x = 1,031.12

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.