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Finding the Fourth Proportional to 1,390.69, 1,919.24 and 769.69

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Solution

The fourth proportional to 1,390.69, 1,919.24 and 769.69 is: 1,062.22

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,390.69 : 1,919.24 = 769.69 : x
  2. Step 2: Convert to fraction form
    1,390.69/1,919.24 = 769.69/x
  3. Step 3: Cross multiply
    1,390.69x = 1,919.24 × 769.69
  4. Step 4: Simplify right side
    1,390.69x = 1,477,214.08
  5. Step 5: Solve for x
    x = 1,477,214.08/1,390.69
  6. Step 6: Final answer
    x = 1,062.22

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Double scale
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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.