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Finding the Fourth Proportional to 1,578.88, 2,178.81 and 989.74

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Solution

The fourth proportional to 1,578.88, 2,178.81 and 989.74 is: 1,365.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,578.88 : 2,178.81 = 989.74 : x
  2. Step 2: Convert to fraction form
    1,578.88/2,178.81 = 989.74/x
  3. Step 3: Cross multiply
    1,578.88x = 2,178.81 × 989.74
  4. Step 4: Simplify right side
    1,578.88x = 2,156,455.41
  5. Step 5: Solve for x
    x = 2,156,455.41/1,578.88
  6. Step 6: Final answer
    x = 1,365.81

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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.