cucumbers puzzle

You had 10lbs of cucumbers, each of which consisted of 99% water. After leaving them in the sun, some of the water in the cucumbers evaporated. If the cucumbers ended up with 98% water in them, how much of their weight did they lose?

The cucumbers lost half of their weight.

If the water was 99% of the total weight, the remaining substance must have weighed 0.1lbs. If after the evaporation the substance comprises 2% = 1/50 of the cucumbers, the total weight must be 50x0.1lbs = 5lbs.