Home / 405.09-559.21-311.80

Finding the Fourth Proportional to 405.09, 559.21 and 311.80

Calculator

Solution

The fourth proportional to 405.09, 559.21 and 311.80 is: 430.42

Step by Step Solution

  1. Step 1: Write the proportion equation
    405.09 : 559.21 = 311.80 : x
  2. Step 2: Convert to fraction form
    405.09/559.21 = 311.80/x
  3. Step 3: Cross multiply
    405.09x = 559.21 × 311.80
  4. Step 4: Simplify right side
    405.09x = 174,360.12
  5. Step 5: Solve for x
    x = 174,360.12/405.09
  6. Step 6: Final answer
    x = 430.42

Related Problems

Find fourth proportional to 202.55, 279.60 and 155.90
Half scale
Find fourth proportional to 810.18, 1,118.41 and 623.60
Double scale
Find fourth proportional to 406.09, 560.59 and 312.80
Similar ratio
Find fourth proportional to 607.64, 838.81 and 467.70
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.