Home / 839.82-1,259.86-428.80

Finding the Fourth Proportional to 839.82, 1,259.86 and 428.80

Calculator

Solution

The fourth proportional to 839.82, 1,259.86 and 428.80 is: 643.27

Step by Step Solution

  1. Step 1: Write the proportion equation
    839.82 : 1,259.86 = 428.80 : x
  2. Step 2: Convert to fraction form
    839.82/1,259.86 = 428.80/x
  3. Step 3: Cross multiply
    839.82x = 1,259.86 × 428.80
  4. Step 4: Simplify right side
    839.82x = 540,227.97
  5. Step 5: Solve for x
    x = 540,227.97/839.82
  6. Step 6: Final answer
    x = 643.27

Related Problems

Find fourth proportional to 419.91, 629.93 and 214.40
Half scale
Find fourth proportional to 1,679.64, 2,519.72 and 857.60
Double scale
Find fourth proportional to 840.82, 1,261.36 and 429.80
Similar ratio
Find fourth proportional to 1,259.73, 1,889.79 and 643.20
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.