Answer: 8.3 minutes
Step-by-step explanation:
The time t may be obtained using the speed distance equation s=d/t. Rearranged to solve for time it would be: t=s/v, where s is the distance between the Sun and Earth and v is the speed of light.
Procedure:
1) calculate the number of diferent teams of four members that can be formed (with the ten persons)
2) calculate the number of teams tha meet the specification (two girls and two boys)
3) Divide the positive events by the total number of events: this is the result of 2) by the result in 1)
Solution
1) the number of teams of four members that can be formed are:
10*9*8*7 / (4*3*2*1) = 210
2) Number of different teams with 2 boys and 2 girls = ways of chosing 2 boys * ways of chosing 2 girls
Ways of chosing 2 boys = 6*5/2 = 15
Ways of chosing 2 girls = 4*3/2 = 6
Number of different teams with 2 boys and 2 girls = 15 * 6 = 90
3) probability of choosing one of the 90 teams formed by 2 boys and 2 girls:
90/210 = 3/7
Answer:
The time it takes for the cannonball to hit the ground is 6.49 seconds.
Step-by-step explanation:
You know that the height of the cannonball above the ground, h, in meters, in time, t, in seconds, is found by the function h(t) = -4.9t² + 30.5t + 8.4. You want to calculate the time it takes for the cannonball to hit the ground, that is, the time it takes for the bullet to reach zero height. So, being h(t) = 0 you have:
0 = -4.9t² + 30.5t + 8.4
To solve a quadratic function 0=a*x² + b*x +c, the expression is applied:
In this case, being a = -4.9, b =30.5 and c =8.4 you have:
Solving you get:
t1= -0.26 seconds and t2=6.49 seconds
Since time does not have a negative value, then <u><em>the time it takes for the cannonball to hit the ground is 6.49 seconds.</em></u>
Number 19 I think is if you add the awnser to one of the numbers you where subtracting and you get the other number you where subtracting you are right like...
Lets say you had the problem 3-2 which is obviously 1 but if you did 2+1 it's 3 so that's how you check.