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Finding the Fourth Proportional to 1,388.21, 1,915.68 and 767.21

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Solution

The fourth proportional to 1,388.21, 1,915.68 and 767.21 is: 1,058.72

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,388.21 : 1,915.68 = 767.21 : x
  2. Step 2: Convert to fraction form
    1,388.21/1,915.68 = 767.21/x
  3. Step 3: Cross multiply
    1,388.21x = 1,915.68 × 767.21
  4. Step 4: Simplify right side
    1,388.21x = 1,469,728.85
  5. Step 5: Solve for x
    x = 1,469,728.85/1,388.21
  6. Step 6: Final answer
    x = 1,058.72

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1.5x scale

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.