Answer: 0.0228
Step-by-step explanation:
Given : The mean and the standard deviation of finish times (in minutes) for this event are respectively as :-

If the distribution of finish times is approximately bell-shaped and symmetric, then it must be normally distributed.
Let X be the random variable that represents the finish times for this event.
z score : 

Now, the probability of runners who finish in under 19 minutes by using standard normal distribution table :-

Hence, the approximate proportion of runners who finish in under 19 minutes = 0.0228
Answer:
Option c
Step-by-step explanation:
A system of equations are given to us. And we need to solve them . The given system is
We numbered the equations here . Now put the value of equation 1 in equation 2 that is substituting y = 2x - 3 in eq. 2 .
We got two values of x as 0 & 2 . Alternatively substituting these values we have ,
Thefore the required answer is ,
Radius of a wheel = 13 inch
= 1.08333 ft
circumference of a wheel = 2×pi×r^2
= 2 × (22/7) × 1.08333^2 ft
= 2 × (22/7) × 1.1736 ft
= (44/7)×1.1736 ft
= 51.6384/7 ft
= 7.3769142857 ft
distance covered in one minute = 37 × 60 ft/min
= 2220 ft/min
now, revolution per minute = 2220 / 7.3769142857
= 300.93884
therefore her wheels are making 300.93884 revolutions per minute
Answer:
∠B = 60°
Step-by-step explanation:
They are supplementary angles, which means they add up to 180°.
∠B + ∠A = 180
? + 120 = 180
? = 180 - 120
? = 60°