Home / 409.60-609.60-390.40

Finding the Fourth Proportional to 409.60, 609.60 and 390.40

Calculator

Solution

The fourth proportional to 409.60, 609.60 and 390.40 is: 581.03

Step by Step Solution

  1. Step 1: Write the proportion equation
    409.60 : 609.60 = 390.40 : x
  2. Step 2: Convert to fraction form
    409.60/609.60 = 390.40/x
  3. Step 3: Cross multiply
    409.60x = 609.60 × 390.40
  4. Step 4: Simplify right side
    409.60x = 237,987.84
  5. Step 5: Solve for x
    x = 237,987.84/409.60
  6. Step 6: Final answer
    x = 581.03

Related Problems

Find fourth proportional to 204.80, 304.80 and 195.20
Half scale
Find fourth proportional to 819.20, 1,219.20 and 780.80
Double scale
Find fourth proportional to 410.60, 611.09 and 391.40
Similar ratio
Find fourth proportional to 614.40, 914.40 and 585.60
1.5x scale

Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.