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Finding the Fourth Proportional to 1,891.36, 2,836.90 and 642

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Solution

The fourth proportional to 1,891.36, 2,836.90 and 642 is: 962.95

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,891.36 : 2,836.90 = 642 : x
  2. Step 2: Convert to fraction form
    1,891.36/2,836.90 = 642/x
  3. Step 3: Cross multiply
    1,891.36x = 2,836.90 × 642
  4. Step 4: Simplify right side
    1,891.36x = 1,821,289.80
  5. Step 5: Solve for x
    x = 1,821,289.80/1,891.36
  6. Step 6: Final answer
    x = 962.95

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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.