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Finding the Fourth Proportional to 990.04, 1,366.32 and 978.70

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Solution

The fourth proportional to 990.04, 1,366.32 and 978.70 is: 1,350.67

Step by Step Solution

  1. Step 1: Write the proportion equation
    990.04 : 1,366.32 = 978.70 : x
  2. Step 2: Convert to fraction form
    990.04/1,366.32 = 978.70/x
  3. Step 3: Cross multiply
    990.04x = 1,366.32 × 978.70
  4. Step 4: Simplify right side
    990.04x = 1,337,217.38
  5. Step 5: Solve for x
    x = 1,337,217.38/990.04
  6. Step 6: Final answer
    x = 1,350.67

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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.