chemistry unit 3 november 2016

It is given in question number 3 (e) i that the uncertainty in each burette reading is (+-) 0.05 cm^3 and for the pipette it is (+-)0.04 cm^3 . The burette titre value is 19.45 cm^3 and the pipette value is 10 cm^3 . The question requires calculating the percentage uncertainty of each. The first value I got it correct which is 0.51% . The second value I got 0.8% while the correct answer is 0.4% . Why dont we multiply the 0.04 by 2 as it is done in the burette uncertainty ?