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Finding the Fourth Proportional to 919.50, 1,268.19 and 639.72

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Solution

The fourth proportional to 919.50, 1,268.19 and 639.72 is: 882.31

Step by Step Solution

  1. Step 1: Write the proportion equation
    919.50 : 1,268.19 = 639.72 : x
  2. Step 2: Convert to fraction form
    919.50/1,268.19 = 639.72/x
  3. Step 3: Cross multiply
    919.50x = 1,268.19 × 639.72
  4. Step 4: Simplify right side
    919.50x = 811,286.51
  5. Step 5: Solve for x
    x = 811,286.51/919.50
  6. Step 6: Final answer
    x = 882.31

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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.