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Finding the Fourth Proportional to 1,173.78, 1,619.78 and 642.64

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Solution

The fourth proportional to 1,173.78, 1,619.78 and 642.64 is: 886.82

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,173.78 : 1,619.78 = 642.64 : x
  2. Step 2: Convert to fraction form
    1,173.78/1,619.78 = 642.64/x
  3. Step 3: Cross multiply
    1,173.78x = 1,619.78 × 642.64
  4. Step 4: Simplify right side
    1,173.78x = 1,040,935.42
  5. Step 5: Solve for x
    x = 1,040,935.42/1,173.78
  6. Step 6: Final answer
    x = 886.82

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.