Converting png to pdf with imagemagick: how to set the resolution?

I have an image foo.png which is 1240 * 1754 pixels.

Using imagemagick on OS X, I convert this to a .pdf and specify the resolution to be 150 dots per inch, so its physical format will be exactly an A4 sheet:

convert -units PixelsPerInch -density 150 foo.png bar.pdf

However, if I now check the resolution of the resulting file:

identify -verbosy bar.pdf | grep Resolution

it says:

Resolution: 72x72

Note: the image should not be scaled or resized or anything. It's 1240 * 1754 and should stay that way. I just want to make sure the PDF covers exactly one full A4 sheet, which is the case with these pixel dimensions at 150 dpi.

How do I make sure the resulting .pdf file has the right resolution?

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