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Finding the Fourth Proportional to 1,319.40, 1,820.91 and 987.25

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Solution

The fourth proportional to 1,319.40, 1,820.91 and 987.25 is: 1,362.50

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,319.40 : 1,820.91 = 987.25 : x
  2. Step 2: Convert to fraction form
    1,319.40/1,820.91 = 987.25/x
  3. Step 3: Cross multiply
    1,319.40x = 1,820.91 × 987.25
  4. Step 4: Simplify right side
    1,319.40x = 1,797,682.51
  5. Step 5: Solve for x
    x = 1,797,682.51/1,319.40
  6. Step 6: Final answer
    x = 1,362.50

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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.