I’m a five letter word. Remove my last two letters and I’m a synonym of drag. My second and third letters form an exclamation and my first and second letters are a homophone with a number. What am I?
Towel. Tow is a synonym of drag, ow is an exclamation when you’re hurt (and far more appropriate in mixed company than the four-letter alternatives) and to is a homophone of two.
A man gets ready for bed at 9:45 pm. He makes himself a drink, then turns off the TV and the lights. The night was windy and there was a major storm. The next day he discovers he was the cause of seven deaths. How is this possible?
He lived in a lighthouse as lighthouse keeper. He turned off all the lights by accident, so a ship with 7 passengers couldn’t negotiate the rocky shores. One would think the light switches in a lighthouse would be more clearly marked.
Water. As ice I’m hard and cold, as water vapor I’m hard to hold and I’m always present in the air as humidity (aka water vapor). If the earth ever runs out of water, we’re toast.
Imagine an HIV test that is 95% accurate (false positive rate of 5%) and around 2% of the tested population is infected with HIV. What is the probability that you actually have HIV when your test comes back positive?