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Finding the Fourth Proportional to 990.86, 1,485.79 and 580.80

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Solution

The fourth proportional to 990.86, 1,485.79 and 580.80 is: 870.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    990.86 : 1,485.79 = 580.80 : x
  2. Step 2: Convert to fraction form
    990.86/1,485.79 = 580.80/x
  3. Step 3: Cross multiply
    990.86x = 1,485.79 × 580.80
  4. Step 4: Simplify right side
    990.86x = 862,943.93
  5. Step 5: Solve for x
    x = 862,943.93/990.86
  6. Step 6: Final answer
    x = 870.90

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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.