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Finding the Fourth Proportional to 1,393.80, 2,087.91 and 661.20

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Solution

The fourth proportional to 1,393.80, 2,087.91 and 661.20 is: 990.48

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,393.80 : 2,087.91 = 661.20 : x
  2. Step 2: Convert to fraction form
    1,393.80/2,087.91 = 661.20/x
  3. Step 3: Cross multiply
    1,393.80x = 2,087.91 × 661.20
  4. Step 4: Simplify right side
    1,393.80x = 1,380,526.09
  5. Step 5: Solve for x
    x = 1,380,526.09/1,393.80
  6. Step 6: Final answer
    x = 990.48

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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.