<span>0.25x2+0.8x−8=0
same as 5x^2+16-160=0 no obvious factors for rational roots, so use quadratic formula
−(x−3)(x+9)=0 .... the factors are clearly (x-3) and (x+9), no need for formula
3x² = 9 ..... we see x^2=3, so roots are ± sqrt(3), no need for formula.
−2x2+5x=7 .... here b^2<4ac, definitely use quadratic formula.</span>
Answer:
Step-by-step explanation:
Let X be the random variable for the time needed to grade a randomly chosen first examination paper
X is N(5, 4)
a)
Time taken=11.00-6.50=4hours 10 min=25/6 hours
P(X<25/6) =P(Z<
=0.5-0.0832=0.0168
b) Time >11.10-6.50 = 4 hours 20 mint = 13/3 hours
P(X>13/3) = P(Z>-0.16) = 0.5636
Step-by-step explanation:
V≈2714.34ft³I hope this answer your question.