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Finding the Fourth Proportional to 1,987.12, 2,980.77 and 891.64

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Solution

The fourth proportional to 1,987.12, 2,980.77 and 891.64 is: 1,337.50

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,987.12 : 2,980.77 = 891.64 : x
  2. Step 2: Convert to fraction form
    1,987.12/2,980.77 = 891.64/x
  3. Step 3: Cross multiply
    1,987.12x = 2,980.77 × 891.64
  4. Step 4: Simplify right side
    1,987.12x = 2,657,773.76
  5. Step 5: Solve for x
    x = 2,657,773.76/1,987.12
  6. Step 6: Final answer
    x = 1,337.50

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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.