Thursday

October 20, 2016
Total # Posts: 12,168

**Math**

X Boys in the class. Y Girls in the class. 3x/4 + 2y/3 = 30, Multiply by 12: Eq1: 9x + 8y = 360. x/4 + y/3 = 42-30 = 12, Multiply by 12: Eq2: 3x + 4y = 144. Multiply Eq2 by -3 and add: 9x + 8y = 360 -9x - 12y = -432 Sum: -4y = -72, Y = 18. 3x + 4*18 = 144, X = 24.

*September 3, 2016*

**Math**

Remainder = 13/13 - 7/13 = 6/13. Next-to oldest share = 2/3 * 6/13 = 12/39. Youngest bro. share = 13/13-7/13-12/39 = 39/39-21/39-12/39 = 6/39 = 2/13. 2/13 * x = 6.00, X = $39. = Sum of money shared.

*September 3, 2016*

**profit and loss**

Profit = 0.1 * 100 = $10. 0.1x = 20, X = $200 = New selling price.

*September 2, 2016*

**PHYSICS CLASS 9**

V^2 = Vo^2 + 2a*d. Vo = 40km/h = 40,000m/3600s = 11.11 m/s. V = 0, a = -0.6m/s^2, d = ?.

*August 31, 2016*

**MATH**

80in * 1cm/48in =

*August 31, 2016*

**math**

r = 0.05/52.

*August 31, 2016*

**algebra**

(2-x)/(2+x). A fraction is equal to zero only when the numerator equals zero: 2-x = 0, X = 2.

*August 31, 2016*

**math**

3.96*10^2/1.5*10^6 = 2.64*10^-4.

*August 30, 2016*

**Math **

A craft project requires 5/6 yards of ribbon to make 4 refrigerator magnets.How many inches of ribbon are needed for each magnet?

*August 30, 2016*

**Physics**

d = 300 + 400 m. = 700 m.

*August 30, 2016*

**math**

P1 = Po(1+r)^n. r = 0.04/365 = 0.0001096/day. n = 365Comp./yr. * 2yrs. = 730 Compounding periods. P1 = 1000(1.0001096)^730 = $1083.28. P2 = Po(1+r)^n. Po = P1 = 1083.28. r = 0.045/365 = 0.0001233. n = 365Comp./yr. * 3yrs = 1095 Compounding periods. P2 = Value after 3 yrs. = ?.

*August 29, 2016*

**math**

P = Po(1+r)^n. P = $10,000. Po = Initial deposit = ?. r = 0.06/12 = 0.005 = Monthly % rate. n = 12Comp./yr. * 5yrs. = 60 Compounding periods.

*August 29, 2016*

**Science**

PE = KE, Mgh = 0.5M*V^2, g*h = 0.5V^2, V^2 = 2*g*h = 19.6*10 = 196, V = 14m/s. Momentum = M*V = 50 * 14 = 700 kg-m/s.

*August 28, 2016*

**Physics**

d = Xo*t = 1.94, 4.8 * t = 1.94, t = 0.404 s. h = 0.5g*t^2 = 4.9 * (0.404)^2 = 0.80 m.

*August 26, 2016*

**MATH**

150/450 = 1/3.

*August 25, 2016*

**physics**

Vt = 72,000m/h = 72,000m/3600s = 20 m/s. 1. Fp = (Vs+Vp)/(Vs-Vt) * Ft. Fp = (343+0)/(343-20) * 600 = 637 Hz. 2. Fp = (343+0)/(343+20) * 600 = 567 Hz.

*August 25, 2016*

**Science**

a. V = 16m/2s = 8 m/s. b. V = 8m/s * 1km/1000m * 3600s/h = 28.8 km/h.

*August 24, 2016*

**Physics**

a. d1 = 3.65-1.55 = 2.10 m. = Distance the shield must travel. V^2 = Vo^2 + 2g*d2 = 0. 2g*d2 = -Vo^2, d2 = -Vo^2/2g = -(7.4)^2/-19.6 = 2.79 m. Yes. b. V^2 = 7.4^2 - 19.6*2.10 = 13.6, V = 3.69 m/s. 7.4 - 3.69 = 3.71 = Change in speed. c. V^2 = 7.4^2 + 19.6*2.1 = 95.92, V = 9.79...

*August 24, 2016*

**Physics**

A. V = Vo + g*t. V = 0, Vo = 50/Ft/s, g = -32.2 F/s^2, t = ?. B. h = Vo*t + 0.5g*t^2. t = Value calculated in part A. C. V^2 = Vo^2 + 2g*h. V = 25 Ft/s, Vo = 50 Ft/s, h = ?.

*August 21, 2016*

**physics**

If half life of iodine 131 is 8 days, how much from 32g remain after 40 days (5 half lives).

*August 19, 2016*

**physics question**

h = 29*sin17 = 8.48 m. = ht. of the incline. V1^2 = Vo + 2g*h = 0 + 19.6*8.48 = 166.2, V1 = 12.9 m/s[17o] = Velocity at bottom of the incline. X1 = 12.9*Cos17 = 12.3 m/s. Y1 = 12.9*sin17 = 3.77 m/s. Y2^2 = Y1^2 + 2g*h = 3.77^2 + 19.6*55 = 1092.2, Y2 = 33 m/s. = Final velocity...

*August 17, 2016*

**physics question**

All angles are measured CCW from +x-axis. D = 10[45o] - 12i + 8[150o]. D = 7.07 + 7.07i - 12i - 6.93 + 4i = 0.14 - 0.93i = 0.94mi[-81.4] = 0.94mi[278.6o].

*August 17, 2016*

**physics math**

Vo = 40m/s[30o]. Xo = 40*Cos30 = 34.64 m/s. Yo = 40*sin30 = 20 m/s. V = (34.64x + 20.00y)m/s.

*August 16, 2016*

**physics math**

Vo = 30m/s[60o]. Xo = 30*Cos60 = 15 m/s. Yo = 30*sin60 = 26 m/s. Y = Yo + g*t = 26 - 9.8*5 = -23 m/s. V^2 = 15^2 + (-23)^2 = 754, V = 27.5 m/s.

*August 16, 2016*

**Biology**

How are cohesion and adhesion of water ar linked to photosynthesis

*August 16, 2016*

**Math**

Deposit = $5.00. End of 1st month = 5*2^1 = $10. End of 2nd Month = 5*2^2 = $20. End of 3rd Month = 5*2^3 = $40. End of 8th Month = 5*2^8 = $1280.

*August 15, 2016*

**math**

A. Y = (x+200) + (x+200)*0.05*5. B. Y = x + x*0.045*6.

*August 13, 2016*

**physics**

D = -4 + 6i + 6 = 2 + 6i. D^2 = 2^2 + 6^2 = 40, d = 6.32 Blocks.

*August 13, 2016*

**physics**

The system is in Equilibrium. The sum of all hor. forces = 0: T1*Cos(180-35) + T2 = 0. -0.819T1 = -T2, T1 = 1.22T2. The sum of all vert. forces = 0: T1*sin(180-35) + (-5) = 0, 0.574T1 = 5, T1 = 8.72 kg. 1.22T2 = 8.72, T2 = 7.15 kg.

*August 13, 2016*

**Math**

9 - 2 X = -4. 9 - 2(4x+5) = 9 - 2(- 16+5) = 31.

*August 11, 2016*

**Math**

Note: 3.14/8 Radians = 22.5o.

*August 11, 2016*

**Math**

(3.14/8)/(6.28) * 360 = 22.5o = Angle of elevation. Tan22.5 = (160-100)/d = 60/d, d = ?.

*August 11, 2016*

**Math**

8 Chocolate, 12 Banana, 16 Strawberry, and 20 Blueberry muffins. Note: Each number is increased by 4.

*August 11, 2016*

**math**

(3+x)*(5+x)*8 = 120+34. (3x+15 + x^2+5x)*8 = 154, (x^2+8x+15)*8 = 154, 8x^2 + 64x + 120 = 154, 8x^2 + 64x - 34 = 0, Use Quad. Formula: X = (-64 +- Sqrt(4096+1088))/16 X = (-64 +- 72)/16 = 0.50 cm, or X = - 8.50 cm.(Not valid). Solution: X = 0.50 cm. added. New Dimensions = 3....

*August 10, 2016*

**science**

Fg = 1/6 * 9.8 = 1.63 m/s^2.

*August 10, 2016*

**Physics**

Incomplete.

*August 8, 2016*

**math**

12,000 - (1/12)*12,000 = 12,000 - 1,000 = $11,000. 11,000 - (1/2)*11,000 = 11,000 - 5,500 = $5,500 = Remaining salary.

*August 8, 2016*

**value**

Need to know: 1. The ht. or 2. The angle and length of the incline.

*August 8, 2016*

**algebra**

Please post the problem.

*August 6, 2016*

**Math**

Starting salary = $X. Salary = x + 2000T = x + 2000*9 = X + $18,000 = $18,000 more than starting salary. s

*August 5, 2016*

**Math**

a. P = Po + Po*r*t. P = $10,000, Po = $9700, t = 1 yr. r = Annual % rate = ?. b. P = Po + Po*r*t. Po = $9720, All other inputs remain the same. r = ?.

*August 5, 2016*

**math**

a. Vt = Vo - d*T*Vo. Vt = Value after time t. Vo = Initial value. d = Depreciation rate per year expressed as a decimal. 1500 - 4d*1500 = 800, d = 0.117/yr. b. V = 1500 - 0.117*5*1500 =

*August 3, 2016*

**physics**

a. V^2 = Vo^2 + 2g*h = (-12)^2 + 19.6*40 = 928, V = 30.5 m/s. b. Vo + g*t = 30.5. -12 + 9.8t = 30.5, t = 4.34 s. To reach gnd.

*August 1, 2016*

**physics**

Vo = 30m/s[90o]?. a. Vo*t + 0.5g*t^2 = 20 m. 30*t- 4.9t^2 = 20, -4.9t^2 + 30t - 20 = 0, t = ?. Use Quad. Eq. b. V^2 = Vo^2 + 2g*h = 0. 30^2 - 19.6h = 0, h = ?. c. V = 0 at max. ht. d. V = Vo = 30 m/s.

*August 1, 2016*

**finance math**

P = Po(1+r)^n. Po = $10,000. r = 0.1/2 = 0.05 = Semi-annual % rate expressed as a decimal. n = 2Comp./yr. * 5yrs. = 10 Compounding periods. P = ?. t = 5 yrs. * 12mo/yr. = 60 mo. Monthly Payments = P/t. ]

*August 1, 2016*

**Physics**

V = 8 + 1.5[37o]*4 = 8 + 6[37o] = 8 + 6*Cos37+6*sin37 = 8 + 4.79+3.61i = 12.79 + 3.61i = 13.3m/s[15.8o]

*August 1, 2016*

**physics**

a. 0.5*a*t^2 = 150. 0.5*4.6t^2 = 150, t = 8.1 s. b. 0.5a*t^2 = d + 150. a = 6 ft./s^2, t = 8.1s, d = ?.

*August 1, 2016*

**physics**

Vs = pi*r^2 * h = 3.14*10^2*25 = 7850 cm*3 = Vol. submerged = Vol. of water displaced. Fb = 7850cm^3 * 1g/cm^3 = 7850 g.

*July 31, 2016*

**GEN MATH**

Use Quad. Formula to prob. 1, and 2. 1. x + 2*1/x = 11/3. x = ?. 2. (3x+10)/x^2 = 1. X = ?. 3. x+5)/(x+3-4) = 2. X = ?. Original fraction = x/(x+3).

*July 31, 2016*

**Math Need Help**

a. 100/140 = 0.714 = 71.4 %. Change = 71.4 - 100 = -28.6 % = 28.6% decrease. b. 140/100 = 1.40 = 140%. Change = 140-100 = 40% increase. = The largest change.

*July 27, 2016*

**Math**

P = (Po*r*t)/(1-(1+r)^-t). Po = 150,000-24,000 = $126,000. r = 8.65%/(12*100%) = 0.0072. t = 25yrs. * 12mo./yr. = 300 mo. Monthly Payments = P/t.

*July 27, 2016*

**physics**

a. V^2 = Vo^2 + 2g*h. Vo = 0, g = 9.8 m/s^2, h = 20 m, V = ?. b. V^2 = Vo^2 + 2a^d = 0. V = 0, Vo = V calculated in part a, d = 0.10 m, a = ?.

*July 25, 2016*

**physics**

a. V = Vo + a*t = 20m/s. 35 + a*608t = 0, = 20, a = -0.25 m/s^2. d = Vo*t + 0.5a*t^2. Vo = 35 m/s, t = 60 s., a = -0.25 m/s^2. b. V = Vo + a*t = 0, 20 - 0.25t = 0, t = 80 s.

*July 25, 2016*

**physics**

a. (20+30)/2 = 25 m/s. = Avg. speed. b. 20*t1 = 10,000m., t1 = 500 s. 30*t2 = 10,000m, t2 = 333.3 s. Total time = t1+t2 = 500 + 333.3 = 833.3 s. Avg. speed = (d1+d2)/(t1+t2) = 20,000/833.3 = 24 m/s.

*July 25, 2016*

**math**

25/2 = 12.5 0r 12 Pens.

*July 23, 2016*

**science**

76.6 - 67.7 =

*July 22, 2016*

**science**

Density = 25grams/29.4cm^3 = 0.85 grams/cm^3.

*July 22, 2016*

**physics**

Vo = 26.2 m/s[23o]. Yo = 26.2*sin23 = 10.2 m/s. a. Y^2 = Yo^2 + 2g*h = 0. 10.2^2 - 19.6h = 0, 19.6h = 104.8, h = 5.3 m. d*sin23 = 5.3, d = 13.7 m. up hill.

*July 21, 2016*

**physics**

Vo = 30km/h = 30,000m/3600s = 8.33 m/s. Vc = 192km/h = 192,000m/3600s = 53.3 m/s. Vm = 150 m/s. V = Vo - Vc + Vm

*July 21, 2016*

**Math**

Po - 0.20Po + 0.06Po = $55.12, 0.86Po = 55.12, Po = $64.09 = Original price.

*July 20, 2016*

**Math**

8500 + 350/yr.*5yrs. = 10,250 students = Enrollment in yr. 2000. 350/yr. * 5yrs. = 1750 Students enrolled from 1995 to yr. 2000.

*July 17, 2016*

**math**

8*10^6 * 1h/3600s * 1day/24h = 92.6 = Ninety-third day.

*July 16, 2016*

**math**

4*500k + 10*200k = $4 Million.

*July 16, 2016*

**Physics**

h = 0.5g*t^2 = = 4.9*4^2 = 78.4 m. Y = Yo + g*t = 0 + 9.8*4 = 39.2 m/s. V = Xo + Y = 20 + 39.2i = 44m/s[63o]. d = Xo*t = 20 * 4 = 80 m. from base of bldg.

*July 11, 2016*

**physics**

d1 = 10km/1.6 = 6.25 mi. d1 = r1*t1 = 12.71*t1 = 6.25, t1 = 0.492 h. d2 = (10-2.1)km/1.6 = 4.94 mi. d2 = r2*t1 = r2*0.492 = 4.94, r2 = 10 mi/h. = min. speed to win.

*July 11, 2016*

**physics**

Speed = 10km/29.5min * 1mi/1.6km * 60min/h = 12.71 mi/h.

*July 11, 2016*

**physics**

r1*t = 6, r * (18/60) = 6, r1 = 20 mi/h. r2 * (9/60) = 6, r2 = 40 mi/h. r = (r1+r2)/2 = 60/2 = 30 mi/h. = Avg. speed when driving to and from the theatre.

*July 11, 2016*

**physics**

V = 0.9mi/0.5h = 1.8 mi/h. V = 1.8 mi/h * 1600m/mi * 1h/3600s = 0.8 m/s. V = 0.8m/s * 1km/1000m * 3600s/h * 24h/day = 69.12 km/day.

*July 11, 2016*

**physics**

d = pi*2r/2 = 3.14*30/2 = 47.1 m. D = 2*r = 2*15 = 30 m. r*t = 47.1, r = 47.1/t = 47.1m/120s. = 0.39 m/s. V = D/t = 30m/120s = 0.25 m/s.

*July 11, 2016*

**Math**

Tan x = 5/2 = 2.50, X = 68.2o. Tan y = 1/4 = 0.25, Y = 14.0o. Tan 14 = 10/d1, d1 = 40.1 m. = Distance from bottom of window to foot of tower. Tan 68.2 = d2/40.1, d2 = 100.3 m. = Vert. distance from top of window to top of tower. h = 10m + d2 = 10 + 100.3 = 110.3 m.

*July 10, 2016*

**PHYSICS**

Yes, I agree.

*July 10, 2016*

**PHYSICS**

KE = 0.5M*V^2. V^2 = Vo^2 + 2g*h = 0 + 19.6*3 = 58.8.

*July 10, 2016*

**PreCalculus 1**

d. 16*Tf^2 = 27.25-10 = 17.25. Tf = 1.04 s. Dx = Xo*(Tr+Tf) = 130*2.28 = 296.7 Ft. 327-296.7 = 30.3 Ft. from bottom of fence. d^2 = 30.3^2 + 10^2 = 1019.3, d = 31.9 Ft from top of fence.

*July 7, 2016*

**PreCalculus 1**

Vo = 136Ft/s[17]. Xo = 136*cos17 = 130 Ft/s. Yo = 136*sin17 = 39.8 Ft/s. b. Y = Yo + g*Tr = 0, 39.8 - 32Tr = 0, Tr = 1.244 s. = Rise time. h = 2.5 + 39.8*1.244 - 16*1.244^2 = 27.25 Ft a5ove gnd. 16*Tf^2 = 27.25, Tf = 1.305 s. = Fall time. 1.244+1.305 = 2.549 s. to hit ground. ...

*July 7, 2016*

**Math**

(x,0), (-8,9), (0,y). X = 3y, (3y,0), (-8,9),(0,y). m = (9-0)/(-8-3y) = (y-9)/(0+8), 72/(-8-3y) = y-9, -8y-3y^2+72+27y = 72, -3y^2+19y = 0, y(-3y+19) = 0, Y = 0, -3y+19 = 0, 3y = 19, X = 3y = 19, Y = 6 1/3 = 19/3. m = 9/(-8-19) = -1/3. Y = mx + b = 9, (-1/3)(-8) + b = 9, b = 9...

*July 7, 2016*

**Physics**

M*(V2-V1) = 0.1(-20-30) = -5 = The Change in momentum

*July 7, 2016*

**Pre Calculus**

Log4 65,536 = X. 4^x = 65,536, x*Log 4 = Log 65,536, X = Log 65536/Log 4 = 8.

*July 6, 2016*

**Pre Calculus**

Log3 36 = N, 3^N = 36, Take Log of both sides: N*Log 3 = Log 36, N = Log 36/Log 3 = 3.26. Answer: e. None of these.

*July 6, 2016*

**Analytic geometry**

2. (-8,8), (x,y), (2,2). x-(-8) = 2(-2-x), x+8 = -4-2x, X = -4. y-8 = 2(2-y), Y = 4. (-8,8), (-4,4), (-2,2). m = (4-8)/(4-(-8)) = -1. Y = mx+b = 8, -1*(-8)+b = 8, b = 0. Eq: Y = -x.

*July 6, 2016*

**Analytic geometry**

1. (-3,0), (x,y), (3,-5). (3-(-3) = 2(x-(-3), 6 = 2x+6, X = 0. (-5-0) = 2(y-0), -5 = 2y, Y = -2.5. (-3,0), (0,-2.5), (3,-5). m = (-2.5-0)/(0-(-3)) = -5/6. Y = mx + b, -5x/6 + b = 0, -5*(-3)/6 + b = 0, b = -5/2 = -2.5. Eq: Y = (-5/6)x - 5/2.

*July 6, 2016*

**Physics**

Cos15 = 0.966.

*July 4, 2016*

**Physics**

Ws = M*g = 20 * 9.8 = 196 N. Fp = 196*sin20 = 67 N. Fn = 196*Cos20 - F*sin15 = 184-0.26F. Fs = 0.2(184-0.26F) = 36.8-0.052F. = Static friction. F*Cos15-Fp-Fs = M*a. 0.97F-67-(36.8-0.052F) = M*0 = 0. 0.97F-67-36.8+0.052F = 0, 1.022F = 36.8, F = 36 N.

*July 4, 2016*

**Physics**

Wb =M*g = 30 * 9.8 = 294 N. = Fn. Fap-Fs = M*a, 85-Fs = M*0 = 0, Fs = 85 N. u = Fs/Fn = 85/294 = 0.289.

*July 4, 2016*

**Physics**

M*g = 25 * 9.8 = 245 N. = Wt. of box. Fp = 245*sin40 = 157.5 N. = Force parallel to the incline. Fn = 245*Cos40 = 187.7 N = Force perpendicular(normal) to the incline. Fap-Fp-Fk = M*a. 500-157.5-Fk = 25*0.75, Fk = ?. k = Fk/Fn

*July 4, 2016*

**Math**

P = Po(1+r)^n P = 0.25 * 29,000 = $7,250 To be saved in 2 years. r = 0.10/2 = 0.05 = Semi-annual % rate. n = 2comp./yr. * 2 yrs. = 4 Compounding periods. Po(1.05)^4 = 7250. Po = 7250/1.05^4 = $5964.59 To be invested now. 0

*July 4, 2016*

**physics**

Vo = 20mi/h * 1600m/mi * 1h/3600s = 8.89s. V = 60mi/h = 26.7 m/s. a = (V-Vo)/t = (26.7-8.89)/10.8 = 1.65 m/s^2. d = Vo*t + 0.5a*t^2

*July 2, 2016*

**physics**

Vr = 5.35 + 15.7i = 16.7 mi/h[71.2o] = Resultant velocity.

*July 2, 2016*

**science physics**

F3 = -16N. = 16N.[180o].

*June 30, 2016*

**science physics**

F3 = -16 N. = 16N.[180o].

*June 30, 2016*

**science physics**

F3 = -16 N. = 16N.[180o].

*June 30, 2016*

**science physics**

F1+F2+F3 = 0, 10 + 6 + F3 = 0, F3 = -16 N.

*June 30, 2016*

**math**

Ganga received $X. Gayatri received (36,000/24,000) * x = $1.5x. x + 1.5x = P, X = 0.4P. x + (1.5x-2500) = 0.5P. Replace X with 0.4P: 0.4P + 0.6P = 0.5P + 2500, P = $5000. = Total profit. g

*June 30, 2016*

**Physics**

V^2 = Vo^2 + 2a*d. V = 10.4 m/s, Vo = 5.20 m/s, a = 4.20 m/s, d = ?.

*June 28, 2016*

**science**

V^2 = Vo^2 + 2a*d. V = 0, Vo = 500 m/s, d = 0.10 m, a = ?. "a" will be negative.

*June 28, 2016*

**Maths**

Eq1: 1.4x + 3y = -1. Eq2: -3x + 2y = -12. Multiply Eq1 by -2, Eq2 by 3, and add: -2.8x - 6y = 2 -9x + 6y = -36 Sum: -11.8x = -34, X = 2.88. In Eq1, replace X with 2.88 and solve for Y.

*June 26, 2016*

**ALGEBRA**

Walking rate = r mi/h. Time = (T-3) hrs. r*(T-3) = 6, r = 6/(T-3). Driving rate = 12r mi/h. Time = T hrs. 12r*T = 180, Replace r with 6/(T-3): (12^6/(T-3))*T = 180, 72T/(T-3) = 180, 72T = 180*(T-3), 72T = 180T-540, T = 5 hrs. r = 180mi/5h = 36 mi/h.

*June 25, 2016*

**pysics**

128km/h = 128,000m/3600s = 35.6 m/s. 128km/h * 1mi/1.6km = 80 mi/h.

*June 25, 2016*

**Math: Personal Finance**

V = 20,000 - 0.25*20,000 = 15,000 = Value after 1 yr. 15,000 - 500 = $14,500. = Amt. paid by Ins.

*June 22, 2016*

**Math: Personal Finance**

P = Po*r*t/(1-(1+r)^-t). r = 0.065/12mo. = 0.00542/mo. = Monthly % rate. P = 750/mo. * 360mo. = $270,000. P = (Po*0.00542*360)/(1-1.00542^-360) = 270,000, (Po*1.950)/0.8571 = 270,000, 2.275Po = 270,000, Po = $118,675.38.

*June 22, 2016*

**Personal Finance**

P = Po(1+r)^n = $3,000. r = 0.06/12mo. = 005/mo. n = 12Comp./yr. * 5yrs. = 60 Compounding periods. Po(1.005)^60 = 3000, Po = ?.

*June 20, 2016*