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Finding the Fourth Proportional to 1,409.40, 2,115.72 and 978.48

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Solution

The fourth proportional to 1,409.40, 2,115.72 and 978.48 is: 1,468.84

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,409.40 : 2,115.72 = 978.48 : x
  2. Step 2: Convert to fraction form
    1,409.40/2,115.72 = 978.48/x
  3. Step 3: Cross multiply
    1,409.40x = 2,115.72 × 978.48
  4. Step 4: Simplify right side
    1,409.40x = 2,070,189.71
  5. Step 5: Solve for x
    x = 2,070,189.71/1,409.40
  6. Step 6: Final answer
    x = 1,468.84

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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.