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Finding the Fourth Proportional to 978.08, 1,349.86 and 647.18

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Solution

The fourth proportional to 978.08, 1,349.86 and 647.18 is: 893.18

Step by Step Solution

  1. Step 1: Write the proportion equation
    978.08 : 1,349.86 = 647.18 : x
  2. Step 2: Convert to fraction form
    978.08/1,349.86 = 647.18/x
  3. Step 3: Cross multiply
    978.08x = 1,349.86 × 647.18
  4. Step 4: Simplify right side
    978.08x = 873,602.39
  5. Step 5: Solve for x
    x = 873,602.39/978.08
  6. Step 6: Final answer
    x = 893.18

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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.