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Finding the Fourth Proportional to 1,287.32, 1,931.70 and 638.06

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Solution

The fourth proportional to 1,287.32, 1,931.70 and 638.06 is: 957.45

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,287.32 : 1,931.70 = 638.06 : x
  2. Step 2: Convert to fraction form
    1,287.32/1,931.70 = 638.06/x
  3. Step 3: Cross multiply
    1,287.32x = 1,931.70 × 638.06
  4. Step 4: Simplify right side
    1,287.32x = 1,232,540.50
  5. Step 5: Solve for x
    x = 1,232,540.50/1,287.32
  6. Step 6: Final answer
    x = 957.45

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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.