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Finding the Fourth Proportional to 990.58, 1,367.16 and 642.28

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Solution

The fourth proportional to 990.58, 1,367.16 and 642.28 is: 886.45

Step by Step Solution

  1. Step 1: Write the proportion equation
    990.58 : 1,367.16 = 642.28 : x
  2. Step 2: Convert to fraction form
    990.58/1,367.16 = 642.28/x
  3. Step 3: Cross multiply
    990.58x = 1,367.16 × 642.28
  4. Step 4: Simplify right side
    990.58x = 878,099.52
  5. Step 5: Solve for x
    x = 878,099.52/990.58
  6. Step 6: Final answer
    x = 886.45

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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.