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Finding the Fourth Proportional to 2,139.75, 3,209.63 and 771.75

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Solution

The fourth proportional to 2,139.75, 3,209.63 and 771.75 is: 1,157.63

Step by Step Solution

  1. Step 1: Write the proportion equation
    2,139.75 : 3,209.63 = 771.75 : x
  2. Step 2: Convert to fraction form
    2,139.75/3,209.63 = 771.75/x
  3. Step 3: Cross multiply
    2,139.75x = 3,209.63 × 771.75
  4. Step 4: Simplify right side
    2,139.75x = 2,477,028.09
  5. Step 5: Solve for x
    x = 2,477,028.09/2,139.75
  6. Step 6: Final answer
    x = 1,157.63

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1.5x scale

Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.