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Finding the Fourth Proportional to 2,015, 2,782.90 and 1,387.20

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Solution

The fourth proportional to 2,015, 2,782.90 and 1,387.20 is: 1,915.85

Step by Step Solution

  1. Step 1: Write the proportion equation
    2,015 : 2,782.90 = 1,387.20 : x
  2. Step 2: Convert to fraction form
    2,015/2,782.90 = 1,387.20/x
  3. Step 3: Cross multiply
    2,015x = 2,782.90 × 1,387.20
  4. Step 4: Simplify right side
    2,015x = 3,860,438.88
  5. Step 5: Solve for x
    x = 3,860,438.88/2,015
  6. Step 6: Final answer
    x = 1,915.85

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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.