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Finding the Fourth Proportional to 1,686.21, 2,326.91 and 978.06

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Solution

The fourth proportional to 1,686.21, 2,326.91 and 978.06 is: 1,349.69

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,686.21 : 2,326.91 = 978.06 : x
  2. Step 2: Convert to fraction form
    1,686.21/2,326.91 = 978.06/x
  3. Step 3: Cross multiply
    1,686.21x = 2,326.91 × 978.06
  4. Step 4: Simplify right side
    1,686.21x = 2,275,852.70
  5. Step 5: Solve for x
    x = 2,275,852.70/1,686.21
  6. Step 6: Final answer
    x = 1,349.69

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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.