Answer:
12 years
Step-by-step explanation:
T + 5 = A
Therefore T =A - 5
In three years T = 3+ (A-5)
thus T = A - 2
Also in three years T = 2/3 (A+3)
Equating the two
A -2 = 2/3 (A+3)
3A - 6 = 2A + 6
3A - 2A = 6 + 6
Therefore A = 12
Answer:
a) 20.16; b) 20.49 and 21.51
Step-by-step explanation:
We use z scores for each of these. The formula for a z score is
.
For part a, we want the 20th percentile; this means we want 20% of the data to be lower than this. We find the value in the cells of the z table that are the closest to 0.20 as we can get; this is 0.2005, which corresponds with a z score of -0.84.
Using this, 21 as the mean and 1 as the standard deviation,
-0.84 = (X-21)/1
-0.84 = X-21
Add 21 to each side:
-0.84+21 = X-21+21
20.16 = X
For part b, we want the middle 39%. This means we want 39/2 = 19.5% above the mean and 19.5% below the mean; this means we want
50-19.5 = 30.5% = 0.305 and
50+19.5 = 69.5% = 0.695.
Looking these values up in the cells of the z table, we find those exact values; 0.305 corresponds with z = -0.51 and 0.695 corresponds with z = 0.51:
-0.51 = (X-21)/1
-0.51 = X-21
Add 21 to each side:
-0.51+21 = X-21+21
20.49 = X
0.51 = (X-21)/1
0.51 = X-21
Add 21 to each side:
0.51+21 = X-21+21
21.51 = X
Answer:
Step-by-step explanation:
Without a second equation relating x and y, we can solve 3x - 1/2y = 2 ONLY for x in terms of y or for y in terms of x:
x in terms of y: Multiply all three terms of 3x - 1/2y = 2 by 2, to eliminate the fraction: 6x - y = 4. Now add y to both sides to isolate 6x: 6x = 4 + y.
Last, divide both sides by 6 to isolate x:
x = (4 + y)/6
y in terms of x:
y = 6x - 4
If you want a numerical solution, please provide another equation in x and y and solve the resulting system.