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Finding the Fourth Proportional to 990.21, 1,366.60 and 636.00

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Solution

The fourth proportional to 990.21, 1,366.60 and 636.00 is: 877.75

Step by Step Solution

  1. Step 1: Write the proportion equation
    990.21 : 1,366.60 = 636.00 : x
  2. Step 2: Convert to fraction form
    990.21/1,366.60 = 636.00/x
  3. Step 3: Cross multiply
    990.21x = 1,366.60 × 636.00
  4. Step 4: Simplify right side
    990.21x = 869,153.87
  5. Step 5: Solve for x
    x = 869,153.87/990.21
  6. Step 6: Final answer
    x = 877.75

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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.