Answer:
(5,15)
Step-by-step explanation:
We know that 225 = 15a + 10c, and he purchased a total of 20 tickets, so
a + c = 20, using this, we know that c = 20 - a, we can substitute this for c in 225 = 15a + 10c to get:
225 = 15a + 10(20 - a) =
225 = 15a + 200 - 10a
225 = 5a + 200
25 = 5a
a = 5
Now we substitute 5 for a:
225 = 15a + 10c
225 = 15(5) + 10c
225 = 75 + 10c
150 = 10c
c = 15
so a = 5 and c = 15, the solution is (5,15)
P.S. I'm the guy who did your other question
Answer: 85 degrees
Step-by-step explanation: 20x+5+24x-1=180
44x+4=180
-4 -4
44x=176
division property of equality x=4
20(4)+5=
80+5= 85 degrees
Answer: 
Step-by-step explanation:
Formula : Probability = 
Given , Sam has 4 cards numbered 2,3,5, and 7.
His friend has 4 cards numbered 1,2,6 and 7.
If they both draw one card and put that on table , then the possible combinations of cards would be (2,1) , (2,2), .... (7,6), (7,7).
i.e. Number of possible outcomes would be (S) 4 x 4 = 16
Favorable outcomes that they will choose same number (F) = (2,2) , (7,7)
Now , the probability that they will both choose the same number would be :
Hence, the required probability =
Since the sample size is less than 30, therefore we use
the t statistic.
Let us define the given variables:
N = sample size = 25
X = average score = 76
s = standard deviation = 12
99% Confidence interval
Degrees of freedom = n – 1 = 24
The formula for confidence interval is given as:
CI = X ± t * s / sqrt N
using the standard distribution table, the t value for DF
= 24 and 99% CI is:
t = 2.492
Therefore calculating the CI using the known values:
CI = 76 ± 2.492 * 12 / sqrt 25
CI = 76 ± 5.98
CI = 70.02, 81.98
Answer: The average score ranges from 70 to 82.
