the amount of gasoline used by a car varies jointly as the distance travelled and the square root of the speed. Suppose a car used 25 liters on a 100 km trip at 100kph, about how many liters will it use on 1000 km trip at 64 kph?

200 litres

Step-by-step explanation:

let g be gasoline used, d the distance travelled and s the speed, then the equation relating the quantities is

g = kd ← k is the constant of variation

To find k use g = 25, d = 100 and s = 100, then

25 = k × 100 × = k × 100 × 10 = 1000k ( divide both sides by 1000 )

0.025 = k

g = 0.025d ← equation of variation

When d = 1000 and s = 64, then

g = 0.025 × 1000 × = 0.025 × 1000 × 8 = 200

the largest number of the four options is 1.8 x 10-2

you have it in scientific notation.

1.80 x 10-6   = 0.00000180

1.80 x 10-4   = 0.000180 (bigger, or "less small", than the former one)

so

1.8 x 10-2       = 0.0180. as you see. the "less small", or the biggest one of them all.

as you have negative exponent, it means you are dividing 1.8 by 100 (i.e. moving the dot towards left, two times).

if you had positive exponent for the scientific notation, power of tenths, you would be multiplying times 100 (moving the dot towards right) as below:

1.8 x (10)2 = 180

so. if you have negative exponent in scientific notation, move the dot toward left. if it is positive, toward right as many times the exponent tells you.

the multiples of 15 are 15, 30,45, 60, 75, 90, 105, 120, 135, 150, 165, 180, 195,   210, 225, 240, 255, 270, 285, 300, 315, 330, 345, 360, 375,   390, 405, 420, 435, 450, 465, 480, 495, 510, 525, 540, 555, 570, 585, 600, 615, 630, 645, 660, 675, 690, 705, 720, and 735.

the factors of 15 are 1, 3, 5, and 15.

hope that , fam!

-une, your fren : )