Answer:
9 mph
Step-by-step explanation:
-let x be the speed of current and t be time. The speed equation for both directions can then be represented as:

#Since t is equal in both, we can do away with t.
#We the divide the downstream equation by the upstream equation as:

Hence, the boat's speed in still water is 9 mph
Answer:
So, 
Step-by-step explanation:

To evaluete this expression we apply exponential property

IF any expression has exponent 0 then the value is 1 always
for example, 

because exponent is 0
So, 
Answer:
a) Null and alternative hypothesis:

b) A Type I error is made when a true null hypothesis is rejected. In this case, it would mean a conclusion that the proportion is significantly bigger than 10%, when in fact it is not.
c) The consequences would be that they would be more optimistic than they should about the result of the investment, expecting a proportion of students that is bigger than the true population proportion.
d) A Type II error is made when a false null hypothesis is failed to be rejected. This would mean that, although the proportion is significantly bigger than 10%, there is no enough evidence and it is concluded erroneously that the proportion is not significantly bigger than 10%
e) The consequences would be that the investment may not be made, even when the results would have been more positive than expected from the conclusion of the hypothesis test.
Step-by-step explanation:
a) The hypothesis should be carried to test if the proportion of students that would eat there at least once a week is significantly higher than 10%.
Then, the alternative or spectulative hypothesis will state this claim: that the population proportion is significantly bigger than 10%.
On the contrary, the null hypothesis will state that this proportion is not significantly higher than 10%.
This can be written as:

Answer:
B
Step-by-step explanation:
Answer:
Caja de plaquetas = x = 30 €
Caja de azulejos = y = 35 €
Step-by-step explanation:
Deje que el costo de
Caja de plaquetas = x
Cuadro de mosaico = y
Por Berta
Para reformar su cocina, Berta compró la semana pasada 2 cajas de baldosas de plaquetas para el suelo y 4 cajas de baldosas para la pared por 200 €.
2x + 4y = 200 ...... Ecuación 1
Hoy
Hoy compré 2 cajas más de plaquetas y otras 2 de tejas por 130 €.
2x + 2y = 130 ..... Ecuación 2
Resolvemos usando el método de Eliminación
2x + 4y = 200 ...... Ecuación 1
2x + 2y = 130 ..... Ecuación 2
Restar la ecuación 2 de 1
2 años = 70
y = 70/2
y = 35 €
Resolviendo para x
2x + 4y = 200 ...... Ecuación 1.
2x + 4 × 35 = 200
2x + 140 = 200
2x = 200 - 140
2x = 60
x = 60/2
x = 30 €
el costo de
Caja de plaquetas = x = 30 €
Caja de azulejos = y = 35 €