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Finding the Fourth Proportional to 1,389.64, 1,917.64 and 768.64

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Solution

The fourth proportional to 1,389.64, 1,917.64 and 768.64 is: 1,060.69

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,389.64 : 1,917.64 = 768.64 : x
  2. Step 2: Convert to fraction form
    1,389.64/1,917.64 = 768.64/x
  3. Step 3: Cross multiply
    1,389.64x = 1,917.64 × 768.64
  4. Step 4: Simplify right side
    1,389.64x = 1,473,974.81
  5. Step 5: Solve for x
    x = 1,473,974.81/1,389.64
  6. Step 6: Final answer
    x = 1,060.69

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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.