Home / 638.40-958.80-395.40

Finding the Fourth Proportional to 638.40, 958.80 and 395.40

Calculator

Solution

The fourth proportional to 638.40, 958.80 and 395.40 is: 593.84

Step by Step Solution

  1. Step 1: Write the proportion equation
    638.40 : 958.80 = 395.40 : x
  2. Step 2: Convert to fraction form
    638.40/958.80 = 395.40/x
  3. Step 3: Cross multiply
    638.40x = 958.80 × 395.40
  4. Step 4: Simplify right side
    638.40x = 379,109.52
  5. Step 5: Solve for x
    x = 379,109.52/638.40
  6. Step 6: Final answer
    x = 593.84

Related Problems

Find fourth proportional to 319.20, 479.40 and 197.70
Half scale
Find fourth proportional to 1,276.80, 1,917.60 and 790.80
Double scale
Find fourth proportional to 639.40, 960.30 and 396.40
Similar ratio
Find fourth proportional to 957.60, 1,438.20 and 593.10
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.