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Finding the Fourth Proportional to 990.72, 1,355.36 and 986.56

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Solution

The fourth proportional to 990.72, 1,355.36 and 986.56 is: 1,349.67

Step by Step Solution

  1. Step 1: Write the proportion equation
    990.72 : 1,355.36 = 986.56 : x
  2. Step 2: Convert to fraction form
    990.72/1,355.36 = 986.56/x
  3. Step 3: Cross multiply
    990.72x = 1,355.36 × 986.56
  4. Step 4: Simplify right side
    990.72x = 1,337,143.96
  5. Step 5: Solve for x
    x = 1,337,143.96/990.72
  6. Step 6: Final answer
    x = 1,349.67

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Why These Related Problems?

These problems maintain the same ratio (1.37) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.