unbelievingly

They watch the meter as they fill their gas tanks and stare unbelievingly at the total at the grocery store for just a few bags.

“He was killed for a sandwich?” one asked, unbelievingly.

She flaps open a shade and blinks unbelievingly at the carnival below her.

“Swell chance you have of getting thinner when you will keep nibbling at chocolate creams,” remarked her sister unbelievingly.

“How do they find that out?” asked one, unbelievingly, “a rifle bullet has been known to go pretty fast at times, you know.”