If f(x) = 5x + 40, what is f(x) when x = -5?
1 answer:
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Answer:
a. two-tailed test
b. reject H0 if Z>1.96 or Z<-1.96
c. Z = 1.73
d. we have failed to reject the null hypothesis
e. P-value = 0.0418
Step-by-step explanation:
We will use a Z test to resolve this, an it will be a two-tailed test because the hypothesis statements are not indicating a specific direction for the significant difference (H0 : μ1 = μ2 ; H1 : μ1 ≠ μ2), this also means that the significanclevel will be divided between the both tails (2.5% en each tail for the rejection regions). See attached drawing for reference.
We need to find our critical value:
Zα/2 = Z(0.05/2) = 0.025
If we look for 0.025 in a Z table we will find that the critical value is 1.96 to the right, and by symmetry -1.96 to the left. So our decision rule will be to reject H0 if Z>1.96 or Z<-1.96
The Z test will be done using the next equation:
Z = (x⁻1 - x⁻2) - (μ1 - μ2) / √( σ²1/n1 + σ²2/n2
Because we are testing the null hypothesis we know that μ1 - μ2 must be zero if they are supposed to be equal (H0 : μ1 = μ2), so we calculate as follows:
Z = (100.5 - 98.8) - (0) / √( (3.4)²/38 + (5.8)²/51 = 1.7/0.9817 = 1.73
Z<1.96, therefore we have failed to reject the null hypothesis
The P-value for this test would be represented by the probability of Z being greater than 1.73, so we can look for it in any Z table, finding that its value is 0.0418, and because P-value>0.025 we again confirm that we don't have evidence statistically significant to reject the null hypothesis
Answer:
$21.2
Step-by-step explanation:
From the problem given, we express them as algebra so that we can easily solve;
the total charge on a call greater than 120min is given as;
120x + y(n - 120) = total cost of call
where n is the number of minutes which is greater than 120;
- Ethan paid $26.80 for 175 mins
n = 175min here;
120x + y(175 - 120) = 26.80
120x + 55y = 26.80 ----- (I)
- $32.40 for 210 minutes
n = 210min
120x + y(210 - 120) = 32.4
120x + 90y = 32.4 ----- (II)
Now let us solve both equations for y and x;
120x + 55y = 26.80 ----- (I)
120x + 90y = 32.4 ----- (II)
subtract the two equations;
90y - 55y = 32.4 - 26.8
35y = 5.6
y = = 0.16cents
then x;
120x = 26.8 - 55y from equation I
120x = 26.8 - 55(0.16)
120x = 18
x = = 0.15cents
Find the cost of 140min of talk time;
n =140min;
= 120(0.15) + 0.16(140 - 120)
= 18 + 0.16(20)
= 18 + 3.2
= $21.2