Answer:
1. Western erodes 2 ft/yr; Dunes builds up at 5 ft/yr
2. Sometime in 2006
3. Solve simultaneous equations
Step-by-step explanation:
1. Erosion patterns
(a) Western Beach
In 15 yr, Western Beach erodes from 100 ft to 70 ft.
The rate of erosion is 30 ft/15 yr = 2 ft/yr.
(b) Dunes Beach
In 15 yr, Dunes Beach builds up from 20 ft to 95 ft.
The rate of buildup is 75 ft/15 yr = 5 ft/yr.
2. Beaches with equal width
From the table, it appears that the beaches will have the same width sometime in year 11 (2006).
3. Best approximation
The graph below also shows that it happens part way through year 11 (2006).
We could get an even better solution by calculating the equations of the two lines and solving the simultaneous equations.
The Right Answer:
We need to mutiply all the numbers.
5*-2 = -10
-10*-1 = 10
The Wrong Answer:
(-2)*(-1) gives +2 (a negative number multiplied for another negative gives a positive number).
2*5 = +10
The mean is 85*0.39 = 33.15, while the standard error is sqrt(0.39*0.61/85) = 0.0529. Using the z-score of 1.96, the confidence interval is:33.15 +/- 1.96*0.0529 = (33.05, 33.25)By dividing by 85, this corresponds to a proportion of:(0.3888, 0.3912)
He can cut 5 squares, by making 1 4 × 4, 2 3 × 3 and 2 2 × 2 squares.
You can start with the equation of
(1/6)x8+(1/8)x6+(1/12)x X=3
Multiply by common denominator of 24 to get
32+18+2x=72
Simplify it we get
50+2x=72
Eliminate using algebra (because it’s add 50 take away the 50 on both sides)
2x=22
Because it’s X2 divide by 2 on both sides
x=11
It will take 11 days
