Answer:
It will take 4 minutes and 30 seconds for hot coffee to cool to a temperature of 25 ° C
Step-by-step explanation:
This problem can be modeled by a first order equation
T(t) = TA + kt
In which TA is the temperature at instant zero and r is the rate of warming(g>0) or cooling(k<0). t is the time in minutes.
The initial temperature of the cup of coffee is 70ºC. So TA = 70. The temperature cools at the rate of 10ºC per minute, so k = -10. So, the equation of the model is:
T(t) = 70 - 10t
We want to know the instant of time when T = 25, so:
25 = 70 - 10t
10t = 70 - 25
10t = 45
t = 4.5 minutes
It will take 4 minutes and 30 seconds for hot coffee to cool to a temperature of 25 ° C
Step-by-step explanation:
about 7% (not exactly 7%, just about)
The question requires that we have to state the hypothesis:
null hypothesis;H0: u1 < u2, the alternate hypothesis;H1: u1 > u2. The one tail test is what is to be used.
<h3>A.
How to state the hypothesis</h3>
H0: u1 < u2
H1: u1 > u2
The one tail test statistic is what is to be used here
<h3>B.
standard error </h3>

= 1.49
The df = 17 + 15 - 2
= 30
test statistic = 18.9 - 17.4 / 1.49
= 1.007
We have the critical value on excel as T.INV(0.9,30)
= 1.310
E. At 0.1, we can conclude that t-value (1.007) does not lies in the rejection area. We fail to reject the null hypothesis. Hence we conclude that the mean vacation with the unlimited plan is greater.
Read more on statistics here brainly.com/question/7597734
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86.6 ft ≈ 87 ft. You can solve this using by multiplying tan 30° by 150.