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Finding the Fourth Proportional to 1,275.38, 1,913.60 and 689.70

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Solution

The fourth proportional to 1,275.38, 1,913.60 and 689.70 is: 1,034.84

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,275.38 : 1,913.60 = 689.70 : x
  2. Step 2: Convert to fraction form
    1,275.38/1,913.60 = 689.70/x
  3. Step 3: Cross multiply
    1,275.38x = 1,913.60 × 689.70
  4. Step 4: Simplify right side
    1,275.38x = 1,319,809.92
  5. Step 5: Solve for x
    x = 1,319,809.92/1,275.38
  6. Step 6: Final answer
    x = 1,034.84

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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.