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Finding the Fourth Proportional to 842.90, 1,256.67 and 821.61

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Solution

The fourth proportional to 842.90, 1,256.67 and 821.61 is: 1,224.94

Step by Step Solution

  1. Step 1: Write the proportion equation
    842.90 : 1,256.67 = 821.61 : x
  2. Step 2: Convert to fraction form
    842.90/1,256.67 = 821.61/x
  3. Step 3: Cross multiply
    842.90x = 1,256.67 × 821.61
  4. Step 4: Simplify right side
    842.90x = 1,032,492.64
  5. Step 5: Solve for x
    x = 1,032,492.64/842.90
  6. Step 6: Final answer
    x = 1,224.94

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.