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Finding the Fourth Proportional to 1,138.70, 1,571.40 and 641.32

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Solution

The fourth proportional to 1,138.70, 1,571.40 and 641.32 is: 885.01

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,138.70 : 1,571.40 = 641.32 : x
  2. Step 2: Convert to fraction form
    1,138.70/1,571.40 = 641.32/x
  3. Step 3: Cross multiply
    1,138.70x = 1,571.40 × 641.32
  4. Step 4: Simplify right side
    1,138.70x = 1,007,766.32
  5. Step 5: Solve for x
    x = 1,007,766.32/1,138.70
  6. Step 6: Final answer
    x = 885.01

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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.