Total miles:350+150=500
Total hours:4+3=7
Avg speed:500/7=71.429 mph
to be sure that 2 of them will be blue i have to select 7+2=9 balls
7+8=15 balls in the urn
P=9/15
to be sure that 4 of them will be yellow i have to select 8+4=12 balls
P=12/15
The coordinates of the vertex are (h,k) so we can write:-
f(x) = a(x -2)^2 - 4
now when f(x) = -7 x = 1 so:-
-7 = a(1-2)^2 - 4
-7 = a - 4
a = -3
so the vertex formula is
f(x) = -3(x - 2)^2 - 4
standard form:-
f(x) = -3(x^2 - 4x + 4) - 4
= -3x^2 + 12x - 16