800 * 100 = 80000
810 * 99 = 80190
900 * 90 = 81000
1000 * 80 = 80000
(800 + 10n) (100-1n)
=(800 +10(11)) (100 - 11)<span>
(910)(89) = 80990</span>
Answer:
fourth number is 9
Step-by-step explanation:
let 'x' equal the fourth number
(5+7+7+x)/4 = 7
cross-multiply to get:
19 + x = 28
x = 9
Answer:
(-∞, 0) U (8, ∞)
Step-by-step explanation:
Answer:
I should use at least 304 students
Step-by-step explanation:
Margin error (E) = t × sd/√n
E = 40
sd = 300
confidence level (C) = 98% = 0.98
significance level = 1 - C = 1 - 0.98 = 0.02 = 2%
t-value corresponding to 2% significance level and infinity degree of freedom is 2.326
n = (t×sd/E)^2 = (2.326×300/40)^2 = 17.445^2 = 304 (to the nearest integer)
Answer:
90⁰
Step-by-step explanation:
y=cosx
y'= -sinx
eqñ of tangent is y=-x
slope of tangent =-1
we know...
slope of tangent = y' or derivative of y
-sin x = -1
sin x= 1
x = 90⁰
