Home / 640.76-884.39-388.80

Finding the Fourth Proportional to 640.76, 884.39 and 388.80

Calculator

Solution

The fourth proportional to 640.76, 884.39 and 388.80 is: 536.63

Step by Step Solution

  1. Step 1: Write the proportion equation
    640.76 : 884.39 = 388.80 : x
  2. Step 2: Convert to fraction form
    640.76/884.39 = 388.80/x
  3. Step 3: Cross multiply
    640.76x = 884.39 × 388.80
  4. Step 4: Simplify right side
    640.76x = 343,848.89
  5. Step 5: Solve for x
    x = 343,848.89/640.76
  6. Step 6: Final answer
    x = 536.63

Related Problems

Find fourth proportional to 320.38, 442.19 and 194.40
Half scale
Find fourth proportional to 1,281.51, 1,768.77 and 777.60
Double scale
Find fourth proportional to 641.76, 885.77 and 389.80
Similar ratio
Find fourth proportional to 961.13, 1,326.58 and 583.20
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.