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Finding the Fourth Proportional to 1,439.40, 2,159.10 and 978.11

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Solution

The fourth proportional to 1,439.40, 2,159.10 and 978.11 is: 1,467.17

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,439.40 : 2,159.10 = 978.11 : x
  2. Step 2: Convert to fraction form
    1,439.40/2,159.10 = 978.11/x
  3. Step 3: Cross multiply
    1,439.40x = 2,159.10 × 978.11
  4. Step 4: Simplify right side
    1,439.40x = 2,111,837.30
  5. Step 5: Solve for x
    x = 2,111,837.30/1,439.40
  6. Step 6: Final answer
    x = 1,467.17

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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.