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Finding the Fourth Proportional to 1,287.38, 1,931.28 and 638.12

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Solution

The fourth proportional to 1,287.38, 1,931.28 and 638.12 is: 957.28

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,287.38 : 1,931.28 = 638.12 : x
  2. Step 2: Convert to fraction form
    1,287.38/1,931.28 = 638.12/x
  3. Step 3: Cross multiply
    1,287.38x = 1,931.28 × 638.12
  4. Step 4: Simplify right side
    1,287.38x = 1,232,388.39
  5. Step 5: Solve for x
    x = 1,232,388.39/1,287.38
  6. Step 6: Final answer
    x = 957.28

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1.5x scale

Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.