Lizzy: Heather helps her neighbour pick weeds out of her garden. She gets paid 5 cents for every weed she picks. On average, how many seconds can she take to pick a weed if she wants to earn $10 an hour?.
Me: Hmmm, let me think. I think this is the detailed solution:
In an hour, she needs to earn $10 * 100 cents / $1 = 1000 cents. In an hour, she must pick 1000 cents / 5 cents = 200 weeds. There are 1hr * (60 minutes / 1 hr) = 60 minutes in an hour. There are 60 minutes * (60 seconds / 1 minute) = 3600 seconds in an hour. She has 3600 seconds / 200 = 18 seconds to pick each weed. Final answer: 18.