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Finding the Fourth Proportional to 915.62, 1,263.78 and 621.20

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Solution

The fourth proportional to 915.62, 1,263.78 and 621.20 is: 857.41

Step by Step Solution

  1. Step 1: Write the proportion equation
    915.62 : 1,263.78 = 621.20 : x
  2. Step 2: Convert to fraction form
    915.62/1,263.78 = 621.20/x
  3. Step 3: Cross multiply
    915.62x = 1,263.78 × 621.20
  4. Step 4: Simplify right side
    915.62x = 785,060.14
  5. Step 5: Solve for x
    x = 785,060.14/915.62
  6. Step 6: Final answer
    x = 857.41

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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.