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Finding the Fourth Proportional to 978.58, 1,349.49 and 859.78

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Solution

The fourth proportional to 978.58, 1,349.49 and 859.78 is: 1,185.66

Step by Step Solution

  1. Step 1: Write the proportion equation
    978.58 : 1,349.49 = 859.78 : x
  2. Step 2: Convert to fraction form
    978.58/1,349.49 = 859.78/x
  3. Step 3: Cross multiply
    978.58x = 1,349.49 × 859.78
  4. Step 4: Simplify right side
    978.58x = 1,160,264.51
  5. Step 5: Solve for x
    x = 1,160,264.51/978.58
  6. Step 6: Final answer
    x = 1,185.66

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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.