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Finding the Fourth Proportional to 990.92, 1,368.06 and 642.26

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Solution

The fourth proportional to 990.92, 1,368.06 and 642.26 is: 886.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    990.92 : 1,368.06 = 642.26 : x
  2. Step 2: Convert to fraction form
    990.92/1,368.06 = 642.26/x
  3. Step 3: Cross multiply
    990.92x = 1,368.06 × 642.26
  4. Step 4: Simplify right side
    990.92x = 878,650.22
  5. Step 5: Solve for x
    x = 878,650.22/990.92
  6. Step 6: Final answer
    x = 886.70

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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.