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Finding the Fourth Proportional to 1,390.89, 1,919.43 and 769.89

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Solution

The fourth proportional to 1,390.89, 1,919.43 and 769.89 is: 1,062.45

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,390.89 : 1,919.43 = 769.89 : x
  2. Step 2: Convert to fraction form
    1,390.89/1,919.43 = 769.89/x
  3. Step 3: Cross multiply
    1,390.89x = 1,919.43 × 769.89
  4. Step 4: Simplify right side
    1,390.89x = 1,477,749.96
  5. Step 5: Solve for x
    x = 1,477,749.96/1,390.89
  6. Step 6: Final answer
    x = 1,062.45

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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.