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Finding the Fourth Proportional to 990.80, 1,492.90 and 821.24

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Solution

The fourth proportional to 990.80, 1,492.90 and 821.24 is: 1,237.41

Step by Step Solution

  1. Step 1: Write the proportion equation
    990.80 : 1,492.90 = 821.24 : x
  2. Step 2: Convert to fraction form
    990.80/1,492.90 = 821.24/x
  3. Step 3: Cross multiply
    990.80x = 1,492.90 × 821.24
  4. Step 4: Simplify right side
    990.80x = 1,226,029.20
  5. Step 5: Solve for x
    x = 1,226,029.20/990.80
  6. Step 6: Final answer
    x = 1,237.41

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Why These Related Problems?

These problems maintain the same ratio (1.51) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.