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Finding the Fourth Proportional to 1,205.40, 1,805.70 and 691.80

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Solution

The fourth proportional to 1,205.40, 1,805.70 and 691.80 is: 1,036.32

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,205.40 : 1,805.70 = 691.80 : x
  2. Step 2: Convert to fraction form
    1,205.40/1,805.70 = 691.80/x
  3. Step 3: Cross multiply
    1,205.40x = 1,805.70 × 691.80
  4. Step 4: Simplify right side
    1,205.40x = 1,249,183.26
  5. Step 5: Solve for x
    x = 1,249,183.26/1,205.40
  6. Step 6: Final answer
    x = 1,036.32

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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.