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Finding the Fourth Proportional to 1,391.25, 1,919.84 and 761.78

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Solution

The fourth proportional to 1,391.25, 1,919.84 and 761.78 is: 1,051.21

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,391.25 : 1,919.84 = 761.78 : x
  2. Step 2: Convert to fraction form
    1,391.25/1,919.84 = 761.78/x
  3. Step 3: Cross multiply
    1,391.25x = 1,919.84 × 761.78
  4. Step 4: Simplify right side
    1,391.25x = 1,462,496.71
  5. Step 5: Solve for x
    x = 1,462,496.71/1,391.25
  6. Step 6: Final answer
    x = 1,051.21

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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.