There are total of 5 digits, of which we arrange 3 of them.
Therefore using permutations we can find total possible 3-number combinations.
5P3 = 5*4*3 = 60
To be greater than 600 means first digit must be 6. (1 possibility)
A number is even only if last digit is even, 2 or 4. (2 possibilities)
The 2nd digit then can only be 3,5, (2 or 4). (3 possibilities)
The total possible even 3-digit numbers greater than 600 is product of each digit's possibilities.
---> 1*3*2 = 6
Therefore probability is 6/60 = 1/10.
Answer:
x=5, y=2
Step-by-step explanation:
You simply write down what you see:
3x - 4y + 4x - 5y = 17
2x - 3y + 3x - 5y = 9
Then you simplify by grouping the x and the y terms:
7x - 9y = 17
5x - 8y = 9
Now you want to get equal amounts of x or y. Let's go for x. If we multiply the top eq with 5 and the bottom one with -7, we get:
35x - 45y = 85
-35x + 56y = -63
-------------------------+ now we can add them:
11y = 22 divide by -11
y = 2
So 7x - 18 = 17, x =5
Finally, it makes sense to double check by filling in these answers in the original equations, just to see if no mistakes were made:
3*5 - 4*2 = 7
4*5 - 5*2 = 10
7+10 = 17: ok!
2*5 - 3*2 = 4
3*5 - 5*2 = 5
4+5 = 9: ok!
It's B because all the students that attended added together is 320 and 37.5 of 320 is 120
