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Finding the Fourth Proportional to 839.88, 1,158 and 643.08

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Solution

The fourth proportional to 839.88, 1,158 and 643.08 is: 886.66

Step by Step Solution

  1. Step 1: Write the proportion equation
    839.88 : 1,158 = 643.08 : x
  2. Step 2: Convert to fraction form
    839.88/1,158 = 643.08/x
  3. Step 3: Cross multiply
    839.88x = 1,158 × 643.08
  4. Step 4: Simplify right side
    839.88x = 744,686.64
  5. Step 5: Solve for x
    x = 744,686.64/839.88
  6. Step 6: Final answer
    x = 886.66

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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.