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Finding the Fourth Proportional to 1,391.79, 1,920.10 and 919.93

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Solution

The fourth proportional to 1,391.79, 1,920.10 and 919.93 is: 1,269.13

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,391.79 : 1,920.10 = 919.93 : x
  2. Step 2: Convert to fraction form
    1,391.79/1,920.10 = 919.93/x
  3. Step 3: Cross multiply
    1,391.79x = 1,920.10 × 919.93
  4. Step 4: Simplify right side
    1,391.79x = 1,766,357.59
  5. Step 5: Solve for x
    x = 1,766,357.59/1,391.79
  6. Step 6: Final answer
    x = 1,269.13

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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.