Plz explain your answer! i will mark at !

Acertain standardized? test's math scores have a? bell-shaped distribution with a mean of 520 and a standard deviation of 105. complete parts? (a) through? (c)

Plzzz maths ! quadratic sequences=an^2+c 1) 11,17,27,41,59 2) 7,16,31,52,79 3) 6,18,38,66,102 4) 0,9,24,45,72 5) 0,12,32,60,96

Jack did 3/5 of all problems on his weekend homework before sunday. on sunday he solved 1/3 of what was left and the last 4 problems. how many problems were assigned for the weekend?