STRANGELY HIGH RAM USAGE IN DELL INSPIRON 14R 5437?

[broadquicksand799]

My RAM usage is nearly 75%, is it okay? Should I buy another slot of 4Gb RAM?
I do not open heavy programs at all, only multitasking involving word processing tasks and web browsing. I already used Ccleaner to clean the system, nothing changed. I do not install too many programs, only enough (Avira, image viewer programs, chrome, mozilla, vlc player, winrar, I mean, standard stuffs).
I mean, even my desktop (win 7 64 bit) with the same amount of programs, the same way I use it, only consume 38% of its 2 x 1Gb corsair RAM. How come my laptop consume nearly 75% of its 1 x 4Gb RAM? Should I buy another slot of 4Gb RAM?

here is my spec
DELL Inspiron 14R 5437 (Core i3-4010U)
Intel Core i3-4010U, 4GB (1x 4GB) DDR3, 500GB HDD, DVD±RW, NIC, WiFi, Bluetooth, VGA NVIDIA GeForce GT740M 2GB, Camera, 14" HD, Win 8 64bit