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Finding the Fourth Proportional to 1,987.71, 2,979.54 and 891.78

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Solution

The fourth proportional to 1,987.71, 2,979.54 and 891.78 is: 1,336.76

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,987.71 : 2,979.54 = 891.78 : x
  2. Step 2: Convert to fraction form
    1,987.71/2,979.54 = 891.78/x
  3. Step 3: Cross multiply
    1,987.71x = 2,979.54 × 891.78
  4. Step 4: Simplify right side
    1,987.71x = 2,657,094.18
  5. Step 5: Solve for x
    x = 2,657,094.18/1,987.71
  6. Step 6: Final answer
    x = 1,336.76

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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.