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Finding the Fourth Proportional to 1,686.12, 2,326.74 and 978

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Solution

The fourth proportional to 1,686.12, 2,326.74 and 978 is: 1,349.58

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,686.12 : 2,326.74 = 978 : x
  2. Step 2: Convert to fraction form
    1,686.12/2,326.74 = 978/x
  3. Step 3: Cross multiply
    1,686.12x = 2,326.74 × 978
  4. Step 4: Simplify right side
    1,686.12x = 2,275,551.72
  5. Step 5: Solve for x
    x = 2,275,551.72/1,686.12
  6. Step 6: Final answer
    x = 1,349.58

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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.