# Posts by Scott

Total # Posts: 3,379

algebra
looks good

Maths
vertical angles at O alternate interior angles where the diagonals meet the parallel sides AAA

Algebra
let x be 3%, y be 5%, and z be 6% x + y + z = 40000 3 x + 5 y + 6 z = 196000 y = z + 8000 use the 1st two equations to eliminate x then substitute for y to find z substitute back to find x and y

Physics
this is integral calculus the mass of a segment of the rod is ... segment length * lambda lambda = .200 (1 + 1.110 x^3) ... = .200 + .222 x^3 segment length is dx integrate from x = 0 to .83 .200 dx + .222 x^3 dx ... sum the two integrals .166 + .026

Geometry
the longest side is opposite the largest angle since 4^2 + 5^2 > 6^2 ... the largest angle is < 90º ... because 6 is to short to be a hypotenuse so ALL the angles are < 90º ... acute

science
from the equation: every 3 moles of hydrogen result in 2 moles of ammonia (12 / 3) * 2 = ?

Math
where does the equal sign go in the 2nd expression?

science
looks good

physics
the rope being at an angle reduces the effective weight for the friction calculation {87 - [60 sin(15º)]} * .35

College math
7000000 * (1 + .05)^12

science
the force is proportional to the square of the diameter w = (30 / 4.5)^2 * 500 N

Math
for n > 2 ... (n - 1) / 2

SCIENCE
the fly's mass (relative to the bus) means that the momentum of the fly is essentially incorporated into the momentum of the bus depending on the relative velocities, this can mean a massive acceleration for the fly ... more than the fly's structure can tolerate (squish)

Science
ME = PE + KE

physics
system momentum is conserved (5 * 3) - (3 * 2) = 3 * v

science
food scraps is the independent variable odor (stink/smell) is the dependent variable the control is the can without scraps

algebra
82.18 - 100 - 33

Math
this would be VERY easy with a Venn diagram looking at 100 students ... 90 use a backpack ... 50 carry a laptop ... 5 do neither let b equal the number who do both (90 - b) + (50 - b) + b = 100 - 5

maths
if Ali SHARED with 3 friends, everyone probably got 1/4 liter

math
the diagonal of the cube is the diameter of the sphere ... 4?3

Honors science
is the water temperature dependent on the amount of sugar or is the amount of sugar dissolved dependent on the water temperature can you change the water temperature by dissolving more or less sugar or can you change the amount of sugar dissolved by changing the water ...

Math
24 is more easily divided into parts ... divisible by 2, 3, 4, 6, 8, and 12 23 is prime ... no factors other than itself and one 25 is only divisible by 5

Algebra 1
your change is \$10 short 100 - 21.24 = 79.76 ... not 69.76

math
[(9 + 9) / 3] * (5 - 3) = 12

Physics
launch velocity is needed

Math
L = 3 W - 2 ... W = (L + 2) / 3 L * W = 60 ... (L^2 + 2 L) / 3 = 60 L^2 + 2 L - 180 = 0 use quadratic formula to find L

Science
at the end of the 4th half sec, the velocity is 4 m/s at the end of the 5th half sec, the velocity is 5 m/s the average velocity over the 5th half second is 4.5 m/s

Science
in the last second, the velocity goes from 9.8 m/s to zero the average velocity is 4.9 m/s for one sec

algebra-math
how many ways can 3 people be selected from a group of 15 this is a combination (order not important) ... the notation is ... 15C3 the calculation is ... 15! / [(15 - 3)! * 3!] ... (15 * 14 * 13) / (3 * 2 * 1)

chemistry
is the exponent supposed to be -6?

Math-college
yes

Algebra 2
divide by L ... S/L = 1-r add r, subtract S/L ... r = 1 - S/L bob ... sign in 2nd step ...

Physics0
each mole of CO2 (mass : 44 g) contains Avogadro's number of molecules each molecule is one carbon (atomic # 6), and two oxygen (atomic # 8) ... looks like 22 protons per molecule a tonne is 1000 kg (5E6 / 44) * 6.02E23 * 22

science
the paper is somewhat fragile

Math
r * t = d you have the rates and time for the vehicles the sum of their distances is the distance between towns

Help scott biostats
google "single sample confidence interval" look at the 1st article

chemistry
molar mass Mg ... 24.3 g molar mass magnesium nitrate ... 148.3 g .261 * (42.2 / 24.3) * 148 g

physics
the mass of the recoiling nucleus is ... 238 - 4 r * 234 = v * 4

math
(2160 / p) + 2 = 2160 / (.88 p) 2 p + 2160 = 2160 / .88

trigonometry(height and distance)
the wording of the problem is awkward, but a steeper angle means a shorter shadow h/(s + 5) = tan(45º) ... h = s + 5 ... s = h - 5 h / s = tan(60º) h = h tan(60º) - 5 tan(60º) 5 tan(60º) = h [tan(60º) - 1)

trigonometry(opt math)
h = height of tower d = distance to tower h / d = tan(60º) (h - 20) / d = tan(45º) h / (h - 20) = tan(60º) / tan(45º) h = tan(60º) * (h - 20) h [tan(60º) - 1] = 20 * tan(60º)

biostats
use a z-score table to find the portion of the population below 1.45 sd above the mean looks like about .93 so prob X ? 8 is ... 1 - .93

Algebra
the board area is ... ? * 5^2 the square area is ... 3^2 the probability of landing in the square is ... "square area" / "board area"

math
the hr hand is 1/12 of the way from 12 to 6 ... the min hand is on 6 ... 11/12 * 180º IN ALL ... climb + slide + walk 57 + ?(57^2 + 76^2) + 76

Physics
index liq = index air * sin(60º) / sin(45º)

Algebra
5C3 = ?

Algebra
D = E + 6 D + 9 + E + 6 + 9 = 82 substituting ... (E + 6) + E + 24 = 82

Algebra
4x^2 - 12x - 1x + 3 ... 4 is to 12 as 1 is to 3 4x (x - 3) - 1 (x - 3) (4x - 1) (x - 3) try googling this ... "factoring polynomials british method"

Math
8 * 11 2/3 = 93 1/3 man-hours after 8 man-hr, 6 men must complete the remaining 85 1/3 man-hr 85 1/3 / 6 = ?

Physics
the wiki article for Young's modulus has the formula you need

Physics
22.4 L/mole ... 1/22.4 mole/L number of atoms ... 6.02E23 / 22.4 1 L = 1E3 cm^3

Physics0
look up the formula and use it length * temp change * expansion factor

Physics
the steam density is ... 590 g/m^3 multiply the mass by the heat of vaporization

PHYSICS 05
(a) h = -4.9 t^2 + 10 ... set h=0 and solve for t (b) horizontal velocity remains constant ... displacement = 20.0 * t (c) Vy = g * t (d) see (b) (e) v^2 = (Vx)^2 + (Vy)^2

math
jon does 1/12 per day jony does 1/24 per day together they do 1/12 + 1/24 = 1/8 per day it took jony 3 days to finish ... 3/24 = 1/8 so together, they did 7/8 ... in 7 days 7 + 3 = 10 days for completion

120 * [1 + (d /100)] * (1 + .25)

Algebra
Henry is correct about the slopes being equal he didn't mention, but the intercepts are also equal the lines are the same ... there are an infinite number of solutions if you know the value of one variable, you know the other

Algebra
the system has no unique solution the equations are equivalent...you can make them the same by manipulation ... multiply 1st eqn by 2 ... add 4x + 7 to both sides ... you now have the 2nd eqn

Geometry
a hypotenuse is the side opposite the right angle in a right triangle ... it is also the longest side two sides of a scalene triangle is NOT enough data to solve the triangle ... unless it is a right triangle ... then you can use Pythagoras (a^2+b^2=c^2)

math
1.4 c * 85 2/7% * 90% = 1.0746 c 7.46% above original cost looks like 4)

math
1.4 c * 85 2/7% * 90% = ?

Precalculus 11
in polynomials, all the exponents for the variable are positive x / 3 = 1/3 x^1 3 / x = 3 x^-1

math
r + 1 = d / t r - 1 = d / 2t ... 2(r - 1) = d / t substituting ... 2r - 2 = r + 1

Science physics
to three figures ... 63.9 do you use significant figure rules?

Science physics
the free fall equation is ... h = -4.9 t^2 + 50 set h = 0 and solve for the flight time multiply the flight time by 20 m/s to find the impact spot

Physics
the free fall equation is ... h = -4.9 t^2 + 78.4 t max t is on the axis of symmetry ... t = -78.4 / (2 * -4.9) find max t and plug into free fall equation to find max height time up equals time down, so the flight time is twice max t

math
(45/2 * 3/4 * 2/3) / 1/4 = ?

math
b + g = 24 g = 2b - 9 solve the system by substitution or elimination

math
(150 g / .75 x L)(150 g / x L) = 1 / .75 = 4/3

Math
2 * 6C2

Math
4 + 4C2 + 4C3 + 1

Math
s * r / 100

Math
[40 * 40% * (8000 - 6500)] + ... [40 * (100% - 40%) * (9000 - 6500)]

Calculus
it is an infinite geometric series and there is a formula for it looking at the series sums ... 1/2, 3/4, 7/8, 15/16, 31/32... you should see the pattern and where the sum is going

a) plug the values for the ends of the intervals into the height equation ... the change in height over the time interval is the average velocity b) is calculus allowed? ... dh/dt = -9.8 t -9.8 m/s^2 is gravitational acceleration ... 9.8 m/s downward for each second of ...

Math
remaining enrollment is e * (100% - 20%) * (100% - 15%) * (100% - 50%) dropped = starting - remaining

Math pre algebra 0096
one is any quantity divided by itself 10/13 * 104y/104y = 80y/104y 104/13 = 8

algebra
jointly means multiple variables cost to run dishwasher is the cost to run the ac, multiplied by the ratios of the run time and wattage ... both time and wattage are direct variation ... the ratios are new to old new cost = ... old cost * (new watts / old watts) * (new time / ...

algebra
less time and lower wattage ... how can the cost be more? \$0.45 * [(40/60) / 2] * (122 / 3000)

maths
/3 ... 2 *2 ... 4 *2 ... 8 -7 ... 1

maths
all the values are divisible by 3 A/B must be divisible by 3 ... so A must divisible by 9

physics
energy (kinetic) is proportional to the square of the velocity if the remaining velocity is a half, then the remaining energy is a quarter ... (1/2)^2 = 1/4 the bullet used 3/4 of its energy to penetrate 3 m it will go another meter

math
the prime factors are ... 2, 3, 3; 5, 5; 5, 7 2 * 3 * 3 * 5 * 5 * 7 = 3150 ... * 3 = ?

statistics
this is binomial ... excellent health or not P(e) = .35 ... P(n) = .65 (n + e)^14 ... sum the 1st 4 terms n^14 + 14 n^13 e + 91 n^12 e^2 + 364 n^11 e^3 .65^14 + (14 * .65^13 * .35) + ...

Math
radicals that aren't "even" roots are irrational numbers ... the decimals are infinite if the numbers have a whole root factor, then take that out ?24 = ?4 * ?6 = 2?6 a calculator can give an approximate value, but the radical form is exact

physics
change in velocity ... -4.4 m/s - 6 m/s = -10.4 m/s acceleration = -10.4 m/s / 0.04 s

Physics
a/b the acceleration of the ball is g (gravity) the free-fall equation is ... h = -1/2 g t^2 + 13.0 t + 30.0 ... h is the height from the bottom of the cliff ... t is the flight time d) plug in zero for h to find the flight time c) the time at peak is on the axis of symmetry ...

Physics
e) the impact angle (?) with respect to the pool surface ... tan(?) = vy / vx

Physics
the average speed (S) is ... 402 m / 4.7 s from a zero start, with constant acceleration, the top speed is twice the average ... St = 2 S acceleration is top speed divided by time ... a = St / 4.7 s

physics
ave speed is half of max ... 1.70 rad/s stopping time ... 2.50 ? rad / 1.70 rad/s ang acc ... 3.40 rad/s / stopping time

Physics
average speed is half of top speed (from zero start) rps = rpm / 60 (ave rps) * 0.8 s = revolutions

math
if 2 in equals 75 ft, then 8 in equals 4 times 75 do the same conversion for 3 in area of the park is length times width

precal 2
2000 ft down the mountain is the 6º angle so his distance to the mountain is ... d = 2000 ft / tan(6º) the mountain above 2000 ft is ... h = d * tan(20º) = 2000 * tan(20º) / tan(6º)

Math
for two unknowns (m and n) you need two unique equations for a solution since there is only one complete equation ... the 2nd equation must be similar it seems that the 9 may be a typo ... probably a 6 instead 6m + 3n = 3 (2m + n) = 21

math
(80 - 67) / 8

math
12000 [1 + (.03 / 4)]^(7 * 4)

Physics
the c-o-m is between the c-o-m of the stick and the c-o-m of the stone the centers of mass for the stick and the stone are in their physical centers using some distance (d) from the center of the stick toward the center of the stone ... 2.5 * d = 10 * (40 - 18/2 - d) find d...

Math
the LCM for 15 and 20 is 60 every 60 minutes

physics
potential energy --> kinetic energy --> heat energy energy = m g h (in Joules) energy / specific heat = temp change A) and B) look like the same thing ... energy

Algebra
he drives 220 mi on 5 gal ... 44 mi/gal ... slope is the car's MPG miles on remaining fuel is the range of the car ... range is DEPENDENT on gallons of fuel gallons on x-axis ... range on y-axis no fuel means no range ... both intercepts are zero (the origin)