I need to create a JPEG file with 2953*4132 pixels and 150 DPI as its requirements. When I convert my AI file to JPEG, the dimensions change to 6152*8612 pixels. I'm using CS6
In this case, the DPI setting has no meaning. Graphics produced for web or pixel based media do not have a DPI resolution. But, if you want one Illustrator pixel to be one point, your DPI setting has to be 72, simply because one point is assumed to be one pixel. One point equals 1/72th of an inch, so if you really put 150 in your dialog that would explain why you get about double the size.
Rule of thumb: if you didn't measure things in physical units, then you do not set DPI because it's meaningless.
In AI CS6 choose Save for Web or ALT+Shift+CTRL+S Then you can provide your dimension you target and option to choose the exporting format (GIF, Jpg, Jpeg, PNG, ...) I hope this will help