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Finding the Fourth Proportional to 999.72, 1,376.64 and 978.12

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Solution

The fourth proportional to 999.72, 1,376.64 and 978.12 is: 1,346.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    999.72 : 1,376.64 = 978.12 : x
  2. Step 2: Convert to fraction form
    999.72/1,376.64 = 978.12/x
  3. Step 3: Cross multiply
    999.72x = 1,376.64 × 978.12
  4. Step 4: Simplify right side
    999.72x = 1,346,519.12
  5. Step 5: Solve for x
    x = 1,346,519.12/999.72
  6. Step 6: Final answer
    x = 1,346.90

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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.