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Finding the Fourth Proportional to 1,271.02, 1,905.80 and 686.70

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Solution

The fourth proportional to 1,271.02, 1,905.80 and 686.70 is: 1,029.66

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,271.02 : 1,905.80 = 686.70 : x
  2. Step 2: Convert to fraction form
    1,271.02/1,905.80 = 686.70/x
  3. Step 3: Cross multiply
    1,271.02x = 1,905.80 × 686.70
  4. Step 4: Simplify right side
    1,271.02x = 1,308,712.86
  5. Step 5: Solve for x
    x = 1,308,712.86/1,271.02
  6. Step 6: Final answer
    x = 1,029.66

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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.