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Finding the Fourth Proportional to 1,389.88, 1,918.30 and 917.80

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Solution

The fourth proportional to 1,389.88, 1,918.30 and 917.80 is: 1,266.74

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,389.88 : 1,918.30 = 917.80 : x
  2. Step 2: Convert to fraction form
    1,389.88/1,918.30 = 917.80/x
  3. Step 3: Cross multiply
    1,389.88x = 1,918.30 × 917.80
  4. Step 4: Simplify right side
    1,389.88x = 1,760,610.37
  5. Step 5: Solve for x
    x = 1,760,610.37/1,389.88
  6. Step 6: Final answer
    x = 1,266.74

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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.