The man was a checkout clerk at the grocery store. The list was for items to get at a lingerie store.

If you answered 1/2, you’re not without comrades, but the generally accepted answer by statisticians (though not without debate) is 1/3. This is because there are four possible combinations: boy-boy, boy-girl, girl-boy and girl-girl. Since we are told one of the children is a boy (but we don’t know if it’s the first or second child), we can rule out the girl-girl combination, leaving three remaining options. Only one out of 3 is boy-boy, so we get a 1/3 chance.

This is a well-known problem known as the Boy or Girl paradox. The other variation is this brain teaser.

Glass.

8. The numbers are in reverse alphabetical order.

Two, three, six, seven, one, nine, four, five, eight.

Malcolm is 6.
The father is 42. 42 days = 6 weeks.
The grandfather is 72. 72 months = 6 years.