Answer:
The 90% confidence interval for population mean is 
Step-by-step explanation:
From the question we are told that
The sample mean is 
The confidence level is 
The sample size is 
The standard deviation
Now given that the confidence level is 0.90 the level of significance is mathematically evaluated as
Next we obtain the critical value of 
from the standardized normal distribution table. The values is 
The reason we are obtaining critical values for instead of that of 
is because represents the area under the normal curve where the confidence level 1 - (90%) did not cover which include both the left and right tail while is just considering the area of one tail which is what we required calculate the margin of error
Generally the margin of error is mathematically evaluated as
substituting values
The 90% confidence level interval is mathematically represented as
substituting values
Answer:
≥ 420 boards
Step-by-step explanation:
Write the required relation between cost per board and "x" (the number of boards that must be sold).
143 + 30240/x ≤ 215 . . . . . . . note that the first term is <em>not</em> 143x
Subtract 143
30240/x ≤ 72
Multiply by x/72. This is a positive number because x is a positive number.
30240/72 ≤ x
420 ≤ x
At least 420 surfboards must be sold to limit the final cost per board to $215.
Answer:
The total charge to her account balance is $83.22
Step-by-step explanation:
We are told that she initially spends $36.50 at the clothing store plus 8% tax.
8% of $36.50 is:
8 / 100 * 36.50 = $2.92
Her total spending at the clothes store is therefore
$36.50 + $2.92 = $39.42
She then spend $25 to refuel her car.
She then bought groceries worth $23.50 and handed over a coupon for a 20% discount on her purchase.
20% discount means 20% of her cost was deducted from what she was supposed to pay and she only paid 80% of the amount she was supposed to pay.
80% of $23.50 is:
80 / 100 * 23.50 = $18.80
Therefore, her total cost (change in her account balance) is:
$39.42 + $25 + $18.80 = $83.22
The total charge to her account balance is $83.22.
18×3=54
3.99×2=7.98
54+7.98+45=106.98
106.98×.085=9.0933
106.98+9.0933=116.0733
rounded to 116.07
answer 116.07
Use the calculator online or on ur phone it should help cause I'm not sure I think its 5=ef
