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Finding the Fourth Proportional to 857.49, 1,287.75 and 638.18

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Solution

The fourth proportional to 857.49, 1,287.75 and 638.18 is: 958.40

Step by Step Solution

  1. Step 1: Write the proportion equation
    857.49 : 1,287.75 = 638.18 : x
  2. Step 2: Convert to fraction form
    857.49/1,287.75 = 638.18/x
  3. Step 3: Cross multiply
    857.49x = 1,287.75 × 638.18
  4. Step 4: Simplify right side
    857.49x = 821,813.49
  5. Step 5: Solve for x
    x = 821,813.49/857.49
  6. Step 6: Final answer
    x = 958.40

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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.