If we represent Tobin's speed as x, we can write her opponent's speed as
x-2 (since Tobin is 2 more than them). In addition, since it's in miles per hour, and 45 minutes is 3/4 of an hour, we can say that 3/4ths of her speed in miles per hour is how long the race is, so (3/4)(x-2)=distance of race. In addition, since it only took Tobin 30 minutes, and 30 minutes is half an hour, x/2 (half of her miles per hour) is the length of the race, so (3/4)(x-2)=(1/2)x. Expanding it, we get 3x/4-6/4=x/2. Subtracting x/2 (or 2x/4) from both sides, we get x/4-6/4=0 and by adding 6/4 to both sides we get x/4=6/4. Multiplying 4 to both sides, we get that x=6=Tobin's speed in miles per hour
<span>We know I kilometer = 0.62 miles and 1 liter = 0.26 gallon. Therefore, 12.4 km/liter = 12.4 * 0.62 miles / 0.26 gallon = 29.56 miles/gallon or we can right as aprproximately 30 miles/gallon. Thus, 12.4 km/l corresponds to 30 miles/gallon.</span>
Step-by-step explanation:
x=20
y=100
solution in image
Answer:
Mean age: 48
Standard deviation: 4
Step-by-step explanation:
a) Mean
The formula for Mean = Sum of terms/ Number of terms
Number of terms
= 42 + 54 + 50 + 54 + 50 + 42 + 46 + 46 + 48+ 48/ 10
= 480/10
= 48
The mean age is 48
b) Standard deviation
The formula for Standard deviation =
√(x - Mean)²/n
Where n = number of terms
Standard deviation =
√[(42 - 48)² + (54 - 48)² + (50 - 48)² +(54 - 48)² + (50 - 48)² +(42 - 48)² + (46 - 48)² + (46 - 48)² + (48 - 48)² + (48 - 48)² / 10]
= √-6² + 6² + 2² + 6² + 2² + -6² + -2² + -2² + 0² + 0²/10
=√36 + 36 + 4 + 36 + 4 + 36 + 4 + 4 + 0 + 0/ 10
=√160/10
= √16
= 4
The standard deviation of the ages is 4
