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Finding the Fourth Proportional to 978.36, 1,350.20 and 646.21

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Solution

The fourth proportional to 978.36, 1,350.20 and 646.21 is: 891.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    978.36 : 1,350.20 = 646.21 : x
  2. Step 2: Convert to fraction form
    978.36/1,350.20 = 646.21/x
  3. Step 3: Cross multiply
    978.36x = 1,350.20 × 646.21
  4. Step 4: Simplify right side
    978.36x = 872,512.74
  5. Step 5: Solve for x
    x = 872,512.74/978.36
  6. Step 6: Final answer
    x = 891.81

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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.