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Finding the Fourth Proportional to 990.40, 1,486.80 and 787.50

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Solution

The fourth proportional to 990.40, 1,486.80 and 787.50 is: 1,182.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    990.40 : 1,486.80 = 787.50 : x
  2. Step 2: Convert to fraction form
    990.40/1,486.80 = 787.50/x
  3. Step 3: Cross multiply
    990.40x = 1,486.80 × 787.50
  4. Step 4: Simplify right side
    990.40x = 1,170,855
  5. Step 5: Solve for x
    x = 1,170,855/990.40
  6. Step 6: Final answer
    x = 1,182.20

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.