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Finding the Fourth Proportional to 1,291.78, 1,937.04 and 642.88

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Solution

The fourth proportional to 1,291.78, 1,937.04 and 642.88 is: 964.01

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,291.78 : 1,937.04 = 642.88 : x
  2. Step 2: Convert to fraction form
    1,291.78/1,937.04 = 642.88/x
  3. Step 3: Cross multiply
    1,291.78x = 1,937.04 × 642.88
  4. Step 4: Simplify right side
    1,291.78x = 1,245,284.28
  5. Step 5: Solve for x
    x = 1,245,284.28/1,291.78
  6. Step 6: Final answer
    x = 964.01

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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.