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Finding the Fourth Proportional to 978.74, 1,351.30 and 647.72

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Solution

The fourth proportional to 978.74, 1,351.30 and 647.72 is: 894.28

Step by Step Solution

  1. Step 1: Write the proportion equation
    978.74 : 1,351.30 = 647.72 : x
  2. Step 2: Convert to fraction form
    978.74/1,351.30 = 647.72/x
  3. Step 3: Cross multiply
    978.74x = 1,351.30 × 647.72
  4. Step 4: Simplify right side
    978.74x = 875,264.04
  5. Step 5: Solve for x
    x = 875,264.04/978.74
  6. Step 6: Final answer
    x = 894.28

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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.