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Finding the Fourth Proportional to 1,689.84, 2,331.84 and 991.20

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Solution

The fourth proportional to 1,689.84, 2,331.84 and 991.20 is: 1,367.77

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,689.84 : 2,331.84 = 991.20 : x
  2. Step 2: Convert to fraction form
    1,689.84/2,331.84 = 991.20/x
  3. Step 3: Cross multiply
    1,689.84x = 2,331.84 × 991.20
  4. Step 4: Simplify right side
    1,689.84x = 2,311,319.81
  5. Step 5: Solve for x
    x = 2,311,319.81/1,689.84
  6. Step 6: Final answer
    x = 1,367.77

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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.