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Finding the Fourth Proportional to 938.28, 1,290.42 and 821.64

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Solution

The fourth proportional to 938.28, 1,290.42 and 821.64 is: 1,130.00

Step by Step Solution

  1. Step 1: Write the proportion equation
    938.28 : 1,290.42 = 821.64 : x
  2. Step 2: Convert to fraction form
    938.28/1,290.42 = 821.64/x
  3. Step 3: Cross multiply
    938.28x = 1,290.42 × 821.64
  4. Step 4: Simplify right side
    938.28x = 1,060,260.69
  5. Step 5: Solve for x
    x = 1,060,260.69/938.28
  6. Step 6: Final answer
    x = 1,130.00

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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.