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Finding the Fourth Proportional to 990.90, 1,368.08 and 636.98

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Solution

The fourth proportional to 990.90, 1,368.08 and 636.98 is: 879.44

Step by Step Solution

  1. Step 1: Write the proportion equation
    990.90 : 1,368.08 = 636.98 : x
  2. Step 2: Convert to fraction form
    990.90/1,368.08 = 636.98/x
  3. Step 3: Cross multiply
    990.90x = 1,368.08 × 636.98
  4. Step 4: Simplify right side
    990.90x = 871,434.35
  5. Step 5: Solve for x
    x = 871,434.35/990.90
  6. Step 6: Final answer
    x = 879.44

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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.