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Finding the Fourth Proportional to 990.50, 1,365.60 and 812.80

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Solution

The fourth proportional to 990.50, 1,365.60 and 812.80 is: 1,120.61

Step by Step Solution

  1. Step 1: Write the proportion equation
    990.50 : 1,365.60 = 812.80 : x
  2. Step 2: Convert to fraction form
    990.50/1,365.60 = 812.80/x
  3. Step 3: Cross multiply
    990.50x = 1,365.60 × 812.80
  4. Step 4: Simplify right side
    990.50x = 1,109,959.68
  5. Step 5: Solve for x
    x = 1,109,959.68/990.50
  6. Step 6: Final answer
    x = 1,120.61

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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.