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Finding the Fourth Proportional to 879.72, 1,213.86 and 647.40

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Solution

The fourth proportional to 879.72, 1,213.86 and 647.40 is: 893.30

Step by Step Solution

  1. Step 1: Write the proportion equation
    879.72 : 1,213.86 = 647.40 : x
  2. Step 2: Convert to fraction form
    879.72/1,213.86 = 647.40/x
  3. Step 3: Cross multiply
    879.72x = 1,213.86 × 647.40
  4. Step 4: Simplify right side
    879.72x = 785,852.96
  5. Step 5: Solve for x
    x = 785,852.96/879.72
  6. Step 6: Final answer
    x = 893.30

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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.