At 9:00 AM, a person running a race was 2 1/2 miles from the start. By 11:30 AM, he was 13 miles from the start. From 9:00 AM to 11:30 AM, at what rate was he running per hour?

4.2 miles per/hour

Step-by-step explanation:

we know

speed  total distance covered/ total time taken to cover that distance.

Time from 9:00 Am to 11:30 Am is 2 hours 30 minutes

time = 2 1/2 hours = 5/2 hours

for distance\

By 11:30 AM, he was 13 miles from the start.

so he covered a total distance of 12 miles

At 9:00 AM, a person running a race was 2 1/2 miles from the start

until 9 am he had already ran 2 1/2 miles = 5/2 miles

since we have to take distance travelled from 9 to 11 :30 Am

we need to subtract distance travel until 9 am from total distance traveled until 11:30 pm

Distance travlled from 9:11:30 am = distance traveled from start till 11:30AM -  distance traveled from start till 9 AM

Distance traveled from 9:11:30 am =  13 - 5/2 = (26-5)/2 = 21/2

Thus, speed = 21/2 / 5/2 = 21/5 = 4 1/5 miles/hour = 4.2 miles/hour

Thus, he was running with 4.2 miles per/hour.

la parábola es el lugar

geométrico en el cual los puntos tienen una distancia idéntica, equidistantes,

de un punto denominado foco, f, y una recta denominada directriz

el radio vector de una

parábola es el segmento que existe entre un punto cualquiera y el foco.

por la ecuación se observa

que la parábola abre hacia la derecha, por lo cual podemos usar las siguientes fórmulas

la ecuación ordinaria de la

parábola es y^2 = 4px, donde p es la longitud desde el vértice de la parábola al

foco.

la fórmula de la directriz

es x + p = 0

resolviendo:

y^2-9x = 0

y^2 = 9x

4p = 9, entonces p = 9/4

entonces el foco tendrá la

coordenada f(9/4,0)

la directriz vendrá

expresada por

x + p = 0

x = -p

x = -9/4

el problema indica que la

ordenada es igual a 6, entonces

(6)^2=9x

x = 36/9

x = 4

entonces el punto al cual

hay que obtener la distancia será p(4,6)

calculando se tendrá: pf = 

pf = 6,25 u

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step-by-step explanation: