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Finding the Fourth Proportional to 987.93, 1,361.76 and 668.80

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Solution

The fourth proportional to 987.93, 1,361.76 and 668.80 is: 921.87

Step by Step Solution

  1. Step 1: Write the proportion equation
    987.93 : 1,361.76 = 668.80 : x
  2. Step 2: Convert to fraction form
    987.93/1,361.76 = 668.80/x
  3. Step 3: Cross multiply
    987.93x = 1,361.76 × 668.80
  4. Step 4: Simplify right side
    987.93x = 910,739.16
  5. Step 5: Solve for x
    x = 910,739.16/987.93
  6. Step 6: Final answer
    x = 921.87

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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.