Alex drives at an average speed that is 1/4 of the average speed that Roy's train travels. Alex takes 20 minutes to travel 12 km in her car. Roy travels for 2 hours and 20 minutes on his train. How far does Roy travel to 2 dp?

336.00 km distance of train

Step-by-step explanation:

Alex = 20mins =12km We distribute to 1hr to find 60mins = 36km p/h.

Roy = 2hrs 20 mins and is 4x the speed of the car.

So 36km x 4 p/h =  144km p/h

2hrs and 20 = 144 x 2.3333 = 335.9952 = 336km

336 km

Step-by-step explanation:

"Alex takes 20 minutes to travel 12 km in her car."

Alex's speed = (12 km)/(20 min) = 0.6 km/min

"Alex drives at an average speed that is 1/4 of the average speed that Roy's train travels."

Therefore, Roy's speed is 4 times Alex's speed.

Roy's speed = 4 * 0.6 km/min = 2.4 km/min

Roy travels for 2 hours and 20 minutes = 2 * 60 min + 20 min = 140 min

speed = distance/time

distance = speed * time = 2.4 km/min * 140 min = 336 km

step-by-step explanation: so we look at the formula un = a + (n-1)d

un is the amount of seats

n is the nth term aka row number

a is the original sequence/row number

d is the difference between each term

so in this a=22 d=6 and n can remain as n because we are simply formjng a rule

lets put these in the equation

un=22+(n-1)(6)

this is your answer to part a

however

lets double check that this is correct, we'll try putting it into the second term

un=a+(n-1)d

u2=22+(2-1)(6)

u2=22+6

u2=28

as the question said the second row has 28 seats so now we know the formula we made is correct.

as for part b

un=a+(n-1)

its asking us to find a row with 100 seats.

remember un was the amount of seata so all we do is substitute this in.

un=100 a=22 d=6

un=a+(n-1)d

100=22+(n-1)(6)

so now we simplify to find n which is the row number.

100-22=22+(n-1)(6)-22

78=(n-1)(6)

78/6=(n-1)(6)/6

13=n-1

13+1=n-1+1

14=n

so now we know that in the 14th row there is 100 seats.

hope this and that you understood! its my first time using the app or anyone out on here : p its also me to revise so a bunch! ask more questions if you dont understand ☺

mrbilldoesmath!

answer: a parabola

steps:

(x-1)(x+4)   = x(x+4) - 1(x+4) = (x^2 + 4x) - (x+4)

                = x^2 +4x -x -4   = x^2 +3x -4

which is a parabola

mrb