1. Math: Ratio

    My son had the following word problem and I don't know where to begin:The ratio in the school gym of boys to girls is 4:3. 160 boys left the gym and the ratio became 4:5. How many girls are in the gym?
  2. physics

    (a) How much waste heat is produced by an electrical power station that uses 1.05 multiplied by 1014 J of heat input with an efficiency of 40.0%? (b) What is the ratio of waste heat to work output? (c) How much work is done?
  3. Environmental science

    Estimate the chronic daily intake of 1,1,1-trichloroethane from exposure to city water supply that contains a 1,1,1-trichloroethane concentration equal to the drinking water standard of 0.2 mg/L. Assume the exposed individual is a child who consumes water at the child rate for...
  4. Chemistry

    This problem is 1st order for half life. How long would it take for the concentration of cyclopropane to decrease to 50% of its initial value? to 25% of its initial value? Rate constant is 9.2/s I set up like this... t1/2= 0.693/9.2/s= 0.075s at 50% I can't figure out how to ...
  5. Math

    Tanker boats cannot be in the bay when the depth of water is less or equal to 25 feet. Set up an inequality and solve it graphically to determine all points in time, t, on the interval 0 less than or equal to t less than or equal to 24 when tankers cannot be in the bay. Round ...
  6. Physics

    An air puck of mass 0.289 kg is tied to a string and allowed to revolve in a circle of radius 0.51 m on a horizontal, frictionless table. The other end of the string passes through a hole in the center of the table and a mass of 0.98 kg is tied to it. The suspended mass ...
  7. math

    write the expression for a number used as a factor seventeen times being multiplied by a number used as a factor fourteen times. then write the product as one power
  8. Astronomy

    Please help! I'm really behind and need to catch up. 1. The rings orbiting the Jovian planets may have been small ____ that got too close to the planets long ago. A. Comets B. Asteroids C. Moons D. Meteors 2. What is the composition of the rings around the Jovian planets? A. ...
  9. math

    it is required to find a rational number which is equal to the recurring decimal number 0.327327327...,(a)find the value of 1000x-x (b)hence, express 0.327327327... in the form a/b, where a and b are integers.
  10. Math

    Find the standard divisor for the given population and number of representative seats. Assume the population is equal to 190,000 and the number of seats is 8. d = ______
  11. Math

    1. If the product of 5 and the sum of 10 and a certain number is equal to 15, what is the number? 2. The sum of two consecutive counting numbers divided by their positive difference is 9. Find the larger numbers.
  12. Physics

    When an air capacitor with a capacitance of 300 nF (1 {\rm nF} = 10^{-9}\;{\rm F}) is connected to a power supply, the energy stored in the capacitor is 1.95×10−5 J. While the capacitor is kept connected to the power supply, a slab of dielectric is inserted that ...
  13. Physics

    When an air capacitor with a capacitance of 380 nF (1 {\rm nF} = 10^{-9}\;{\rm F}) is connected to a power supply, the energy stored in the capacitor is 1.95×10−5 J. While the capacitor is kept connected to the power supply, a slab of dielectric is inserted that ...

    Find the standard divisor (to two decimal places) for the given population and number of representative seats. Assume the population is equal to 8,640,000 and number of seats is 15. =
  15. Math

    What is the square of the least two-digit prime number? What is the least two-digit prime number? 11 how do i show that the polygons are similar by checking that corresponding angles have equal measures and corresponding sides are proportional? 10 11 So 112 = ?? 11
  16. Biology

    I am lost in this Genetics Maze. Here is my assignment: Write out a cross using genotypes as parents Determine Possible Gametes that may be formed Use a Punett Square to establish the genotypes of all possible progeny. Determine the Genotype Ratio of the progeny. Count the ...
  17. Pre-Calculus

    Find the twelfth term of the geometric sequence: 1/16, 1/8, 1/4.... Common ratio: 1/2 I got the ratio by dividing 1/16 by 1/8 which gave me 1/2 and I divided 1/8 by 1/4 to get 1/2-----That is how I got a common ratio of 1/2. In order to obtain the 12th term I think I messed up...
  18. physics PLEASE helpp

    Suppose 0.0210 kg of steam (at 100.00°C) is added to 0.210 kg of water (initially at 19.5°C.). The water is inside a copper cup of mass 48.9 g. The cup is inside a perfectly insulated calorimetry container that prevents heat flow with the outside environment. Find the final ...
  19. Pre Calculus 1

    thirty percent of a radioactive substance decays in four years. assuming the decay is exponential, find the half life of the substance. the beginning of 1975 the population of a country was 40 million and growing at a rate of 3% per year. Assume that the growth is exponential...
  20. Pre-Cal

    A piece of charcoal of mass 35g is found in the ruins of an ancient city. The sample shows a carbon-14 activity or R(t)=4.167 decays/sec. Convert the decay constant of ^14C from (1)(a)in terms of seconds instead of yrs. Find the number of atoms N(t)using constant you found.
  21. Physics PLEASE HELP

    After 6.00 kg of water at 77.3 oC is mixed in a perfect thermos with 3.00 kg of ice at 0.0 oC, the mixture is allowed to reach equilibrium. When heat is added to or removed from a solid or liquid of mass m and specific heat capacity c, the change in entropy can be shown to be...
  22. Math.

    1. Tyler has 45 baseball cards and 54 basketball cards. He organized them into equal rows for a display. He did not want to mix the basketball and baseball cards in a row. What was the greatest number of cards in each row? a. Write each number as the product of any two of its ...
  23. algebra 2

    find coordinates of vertices formed by x+yless than or equal to 2 x-2y less than or equal to 8 and x+(-1/3y) greater or equal to -2/3
  24. Infinite math

    use the M method to solve the following linear programming problem: Minimize C+ -5x+10x+15x Subject to 2x+3x+x <(or equal to) 24 x-2x-2x >(or equal to) 1 x,,x,x>(and equal to) 0
  25. MATH

    How many meters equal 1 mile? How many inches equal 1 meter? How many miles equal 1 km? http://www.worldwidemetric.com/metcal.htm
  26. physics

    A mass is attached to a vertical spring, which then goes into oscillation. At the high point of the oscillation, the spring is in the original unstretched equilibrium position it had before the mass was attached; the low point is 8.6cm below this. What is the period of ...
  27. chemistry

    N204 (l) Delta Hf (kJ/mol) = -20 E cell S (J/mol.K) = 209 N204(g) Delta Hf (kJ/mol) = 10 E cell S (j/mol.k) = 304.1 Given the following data, determine the temperature at which n2o4 (l) and n204 (g) can exist in equilibrium? a. 42 C b. 3 C c. -231 C d. 30 C e. -178 C
  28. chemistry

    A reaction starts with 1.00 mol each of PCl3 and Cl2 in a 1.00-L flask. When equilibrium is established at 250 degree Celsius in the reaction PCl3(g)+ Cl2(g)--> PCl5(g), the amount of PCl5 present is 0.82 mol. What is Kc for this reaction?
  29. Physics

    As a traffic light turns green, a waiting car starts with a constant acceleration of 6.0 m/second squared. At the instant the car begins to accelerate, a truck with the constant velocity of 21 m/ second squared passes in the next lane. HINT:Set the 2 distance equations equal ...
  30. Chemistry

    A sample of zinc with a mass of 14g was heated to 98 degree celsius in boiling water and then dropped into a beaker containing 4.5x10^4ng of water at 25 degree celsius. when the water and metal came to thermal equilibrium, the temperature is 29 degree celsius. what is the ...
  31. math trigo

    alfa+bita = thita & tan x ratio tan y= x ratio y then prove that sin alfa- bita = x- y ratio x+y sinthita
  32. Chemistry

    The reaction 2B--->C + 2D is found to be zero order when run at 990 degrees C. If it takes 3.3X110^2 s for an initial concentration of B to go from 0.50 M to .20 M what is the rate constant for the reaction? what is the half life of the reaction under these conditions?
  33. Maths

    What is the largest three-digit number with the property that the number is equal to the sum of its hundreds digit, the square of its tens digit and the cube of its units digit?
  34. Math

    12 girls and 20 boys signed up to play n a basketball tournament. Each team needs to have an equal number of girls and boys. What is the greatest number of teams possible
  35. math

    Hi, for the question, "the sum of two numbers is equal to a third number(x+y=z). The sum of twice the first, three times the second, and twice the third is 7(2x+3y+2x=7). The third number is 3 more than the first(3+z=x), have I set the equations right? I got different answers ...
  36. Maths

    Now suppose that the weight attached to the spring is pulled down a further 5cm from its equilibrium positions and released from rest. Show that newtons second law leads to the dynamic equation (in SI units) d^2z/dt^2 + 36z - g = 0 where z(t) measures the extension of the ...
  37. intro of my essay

    Nuclear power plants have been a controversy issue in our world for many years and it will continue to be so in the years to come. The issue of whether people should or shouldn’t accept power plants to be operated has been widely debated among communities, especially in San ...
  38. math ratio

    The ratio of the distances a driver and a 2 iron can propel a golf ball is 5 to 4. If a golfer averages a distance of 200 yards with a 2 iron, how far should she average with a driver. I get 250 yards is that right? 5/4=x/200 is ratio set-up
  39. Physics

    Power of a car weighing 1200kg is 134.05hp and its efficiency is 90%. How long will it take to raise of the car to 20m/s from rest. solution:v2=u2+2as 400=2as as=200 real power=13.05hp =100001.3W effective power=90001.17W Power=W/t =mas/t =1200*200/t t=90001.17/240000 =2.67s ...
  40. Chem

    An electrochemical cell based on the decomposition of H2O2 can be constructed based on the half-reactions in the table below. Half-Reaction | Standard Reduction Potential, E° H2O2+ 2e- => 2 OH- | 0.88 V O2+ 2 H2O + 2e- => H2O + 2 OH- | -0.15 V (d) Calculate the value of...
  41. Science

    According to Newton’s third law of motion, when a hammer strikes and exerts force on a nail to push it into a piece of wood, the nail (1 point) 1. creates a friction with the hammer. 2. exerts an equal force on the wood. 3. exerts an equal and opposite force on the hammer. 4...
  42. Geometry

    two similar solids have corresponding lengths in the ratio 2:5. Determine the ratio of the lateral area
  43. geometry

    if two cones are similar and the ratio between the lenghts of the radii is 7:3, what is the ratio of their surface areas
  44. math

    determine which ratio forms a porportion with 24/28 by writing the ratio in simplest form A( 3/4 B( 4/6 C( 4/7 D( 7/9
  45. Math

    two cones have radii in the ratio 5:4 and height 2:3, determine the ratio of their volumes . where V=1/3pier^2h
  46. Algebra

    If the ratio of x+y to x−y is 11/4, then the ratio of y to x can be written as a/b where a and b are coprime positive integers. Find a+b .
  47. geometry

    if two cones are similar and the ratio between the lengths of the radii is 7:3, what is the ratio of their surface areas
  48. MATH

    Write each of the following ratios in simplest form. 1. The ratio of 5 3/5 to 2 1/10 A~8 TO 3? 2. The ratio of 7 dimes to 3 quarters A~ 14 TO 15?
  49. geometry

    if two cones are similar and the ratio between the lengths of the radii is 7:3, what is the ratio of their surface areas
  50. Physics

    Two lead spheres at the same temperature have radii in the ratio 1:2.what is the ratio of their heat capacities
  51. Math

    A 274cm timber is cut into three pieces in the ratio 3:7:11,find the length of each ratio.
  52. Math

    The ratio of ages of P andQ in 1996 was2:3 and in 2001was7:10 what will be the ratio in 2011
  53. geometry

    If the ratio of the volume of two similar solids is 8:125, then what is the ratio of their surface areas?
  54. Math

    The ratio of seven dimes to three quarters. It wants me to write this ratio in simpliest form. I really need to understand how to do this. I have a few more like this that I have to do. Thank You
  55. math

    Michel's class had 4 A's, 10B's, 13C's, 8D's, and 2F's What is the ratio of A's to B's and what is the ratio of f's to total students.
  56. Geometry

    How do you find the ratio if the areas of 2 similar triangles in which the ratio of a pair of corresponding sides is 4:1
  57. Chemistry Lab

    We did a lab where we reacted antacid with HCL and measured the pressure increase after the reaction. Then we found the percent concentrations of calcium carbonate of the antacid tablet. The question is: say the percent of calcium carbonate from trials 1 & 2 are consistent ...
  58. Mico

    I have shown my answers that i thought were correct. Do you mind letting me know what you think. Thank you so much. Anything will help!! I have placed an *. By the ones i think are right!! It has been so long since i took micro!! 1. The basic concern of economics is: (Points: ...
  59. physics / electricity question

    A sphere with a mass m and a net charge Q is tied to a string and placed in a uniform electric field E. Once the sphere has come to equilibrium, the string makes an angle theta. Find the charge Q in terms of E, m, and theta. I am not sure how to combine the force of tension ...
  60. physics

    how to determine the amount of water in the container when you are given a 200g piece of aluminium at 90 degrees celcius is placed in a 100g glass container which holds an unknown amount of water at 20 degrees celcius .if the equilibrium temperature is 21.6 degrees celsius(...
  61. high school physics static friction

    The system shown below is in equilibrium. Using the fact that block A is placed on a table, has a normal force of 40.2 N and it is not moving, what is the coefficient of static friction on block A? I know you can't answer this but if you have any suggestions: Calculate the ...
  62. Chemistry

    Dinitrogen tetroxide decomposes to nitrogen dioxide: N2O4 (g) ---> 2NO2 (g) Delta H rxn: 55.3 kJ At 298 K a reaction vessel initially containing .100 atm of N2O4. When equilibrium is reached, 58% of the N2O4 has decomposed to NO2. -What percentage of N2O4 decomposes at 350 ...
  63. Chemistry

    Dinitrogen tetroxide decomposes to nitrogen dioxide: N2O4(g)→2NO2(g)ΔHorxn=55.3kJ At 298 K, a reaction vessel initially contains 0.100 atm of N2O4. When equilibrium is reached, 58% of the N2O4 has decomposed to NO2. What percentage of N2O4 decomposes at 350 K ? Assume that ...
  64. Calculus

    A patient is given a drug intravenously at a rate of 43.2 mg/hour. The drug enters a compartment volume or the volume of the part of the body of 35,000 ml. The rate at which the drug leaves the body (mg/hour) is proportional to the quantity present, with proportionality ...
  65. College Chemistry

    For my homework I got this problem that my professor never went over in class how to do it and I don't know how to interpret it. A chemist runs a second order reaction of A->B starting at 10mili moles/L concentration of A (and no B). After one hour the concentration of the ...
  66. physics

    A speed boat is required to move at a constant speed of 50 MPH. What is the power needed to overcome a resistive force of 1000 lbs from the water?
  67. physics

    An engine moves a motorboat through water at a constant velocity of 22 meters/second. If the force exerted by the motor on the boat is 5.75 × 103 newtons, what is the power of the motor?
  68. Physics

    An engine moves a motorboat through water at a constant velocity of 22 meters/second. If the force exerted by the motor on the boat is 5.75 × 103 newtons, what is the power of the motor?
  69. physics

    find the power by a man if he runs at constant speed of 5km/h along an ascending road which makes 5 degree with the horizontal if the mass of yhe man is 60 kg.
  70. Physics

    A student weighing 673 N climbs at constant speed to the top of an 11 m vertical rope in 14 s. What is the average power expended by the student to overcome gravity?
  71. Physics

    In a game of pool the cue ball strikes another ball of the same mass and initially at rest. After the collision the cue ball moves at 3.50 m/s along a line making an angle of 22 degrees with its original direction of motion. and the second ball had a speed of 2 m/s. a)What is ...
  72. math

    the ratio of the areas of two squares is 9:4. the ratio of their perimeters is (please explain in detail)
  73. Geometry

    If the ratio of the areas of two similar rectangles is 100/81, then what is the ratio of the perimeters?
  74. math

    In a pair of similar rectangles, the ratio of the widths Is 3:4. What is the ratio of the lengths?
  75. geometry

    The ratio of the areas of two similar trapezoids is 1:9. What is the ratio of the lengths of their altitudes?
  76. Math

    How do I find a ratio equivalent to each ratio then use the ratios to write a proportion
  77. Geometry

    If the ratio of the areas of two similar hexagons is 4:49, find the ratio of their apothems
  78. geomatry

    Prove algebraically that the ratio of perimeters of two triangles is 1:4 if the ratio of their corresponding sides is 1:4
  79. math

    Write the ratio in simplest form. The ratio of 75 seconds to 3 minutes.
  80. Physics

    A small bead of mass m and charge q is free to move in a horizontal tube. The tube is placed in between two spheres with charges Q = − q. The spheres are separated by a distance 2a. What is the frequency of small oscillations around the equilibrium point of the bead? You...
  81. chemistry

    What is the final concentration (in M) of 17.6 mL sodium chloride solution with an initial concentration of 1.86 M which is diluted with 18.9 mL of solvent? Assume the volumes are additive.
  82. Microbiology

    if the original concentration of phage was markedly increased from the concentration that you received, how could you ensure that you had between 30-300 plaques on your plate? (instead of TNTC)
  83. Physical Science

    Determine the concentration of the HCl in a swimming pool?given 100ml of a standard solution of Na2CO3 of concentration 0.05mol.dm
  84. Biochemistry

    The concentration of cholesterol in blood from a fasting individual is reported as 185mg %, where mg% is mg/100 mL. Convert this concentration to moles/Liter.
  85. chem

    The solubility product of Mg(OH)2 is 1.2 x 10^-11. What minimum OH- concentration must be attained (for example, by adding NaOH) to decrease the Mg concentration in a solution of Mg(NO3)2 to less than 1.0 x 10^-10 M (molar)?
  86. Chemistry

    How does one calculate the pH of a solution that is only 1.84% ionised? determine the concentration of the H+, which will be in a monoprotic acid, concentration * decimal percent. then determing pH in the normal way.
  87. Chemistry

    What weights of NaH2PO4 and NaHPO4 would be required to prepare a buffer solution of pH 7.45 that has an ionic strength of 0.1? pKa2=7.12 , mwt NaH2Po4=120g/mol NaHPO4=142 g/mol using the henderson-hasselbalch equation i got that the ratio of the concentration of NaH2PO4 to ...
  88. Chemisty

    The Specific heat of a substance is the energy (joules) required to raise one gram of substance by one degree celsius (units J/g °C). Heating 225.0 cm3 of a solid from 36.1 °C to 74.3 °c takes 35850 J of energy. The density of the solid at 36.1 °C is 1.75 g/cm3. What is ...
  89. physics

    For an object travelling at a constant velocity, how does the dispalcement change over equal time intervals? I do not understand this question pls help.
  90. science

    Two particles are moving at a speed v such that they are always at a constant distance d apart and their velocities are always equal and opposite.at what time they return to their initial positions?
  91. Earth Science

    Using Kepler's equal area law, explain why the speed of an object in a perfectly circular orbit is constant. HELP!!!!!!!!!!!!!!
  92. math,(fraction)

    Mr Lim put some red pens and blue pens into a box.The ratio of the number of red pens to the number of blue pens was 3:4. He added 20 red pens into the box and the ratio became 2:1. a. were there more red pens or blue pens in the box at the end? b. how many red pens were there...
  93. Math

    the function KE(v)=(1/2)kv^5 , given that k is a constant,is an example of a power function?
  94. how to understand this

    design and implement such a function and use it in a program called part3.c that allows someone to enter two real numbers and an epsilon value (also a real number) and reports if the two numbers are equal (+/- epsilon) or not. If you were asked this question, how would you try...
  95. Chemistry

    What is ΔG at body temperature (37.0° C) if the concentration of A is 1.7 M and the concentration of B is 0.50 M?
  96. chem sorry the last one did not have the question

    A sample of PCl5 weighing 2.69 grams is placed in a 1.000 liter flask and vaporized completely at 250 o C. The final pressure observed at this temperature is 1.000 atmospheres. Note that some, but not all of the PCl5 decomposes according to the equation: PCl5 (g) --------->...
  97. APChem

    "The osmotic pressure of a saturated solution of strontium sulfate at 25C is 21 torr. What is the solubility product of this salt at 25C (Hint: calculate molarity from the colligative properties eqn of osmotic pressure and use it in the equilibrium expression" I converted torr...
  98. Chemistry/Math

    Write a differential equation describing a second order reaction – a reaction in which the rate of depletion of the concentration of the reactants depends on the square of reactants’ concentration. Solve this differential equation and hence find an expression for the ...
  99. Science

    When the number of gas particles in a container with constant volume decreases, does the pressure of the gas increases? If the number of gas particles at constant pressure increases, will the volume of the gas decrease? What is the relationship between gas particles and volume...
  100. physics

    The length of a simple pendulum is 0.82 m and the mass of the particle (the "bob") at the end of the cable is 0.69 kg. The pendulum is pulled away from its equilibrium position by an angle of 6.7 ° and released from rest. Assume that friction can be neglected and that the ...
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