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Finding the Fourth Proportional to 1,256.80, 1,736.40 and 978.08

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Solution

The fourth proportional to 1,256.80, 1,736.40 and 978.08 is: 1,351.32

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,256.80 : 1,736.40 = 978.08 : x
  2. Step 2: Convert to fraction form
    1,256.80/1,736.40 = 978.08/x
  3. Step 3: Cross multiply
    1,256.80x = 1,736.40 × 978.08
  4. Step 4: Simplify right side
    1,256.80x = 1,698,338.11
  5. Step 5: Solve for x
    x = 1,698,338.11/1,256.80
  6. Step 6: Final answer
    x = 1,351.32

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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.