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Finding the Fourth Proportional to 1,261.68, 1,891.56 and 645.60

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Solution

The fourth proportional to 1,261.68, 1,891.56 and 645.60 is: 967.91

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,261.68 : 1,891.56 = 645.60 : x
  2. Step 2: Convert to fraction form
    1,261.68/1,891.56 = 645.60/x
  3. Step 3: Cross multiply
    1,261.68x = 1,891.56 × 645.60
  4. Step 4: Simplify right side
    1,261.68x = 1,221,191.14
  5. Step 5: Solve for x
    x = 1,221,191.14/1,261.68
  6. Step 6: Final answer
    x = 967.91

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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.