# peter

Most popular questions and responses by peter

38. ## Chemistry

Naturally occurring boron is 80.20% boron-11 (of atomic mass 11.01 amu) and 19.80% of some other isotope form of boron. What must be the atomic mass of this second isotope in order to account for the 10.81 amu average atomic mass of boron? A. 10.99 amu B.

39. ## Maths

A contains some red and blue balls. There are four more red than blue balls. A ball is removed at random and replaced. A second ball is removed. The probability that the two balls are different colours is 21/50. How many balls are in the box. Ans Drawing a

40. ## probability

Poisson Processes and Bayes' Rule We observe a Poisson process with unknown rate. The rate 𝜆 of the Poisson process is either 2 or 4, with equal probability, and the actual value is not known. We observe the process over the time interval [0,3] and

41. ## Science

Consider a piece of gold jewelry that weighs 9.50 g and has a volume of 0.685 cm^3 . The jewelry contains only gold and silver, which have densities of 19.3 g/cm^3 and 10.5 g/cm^3, respectively. If the total volume of the jewelry is the sum of the volumes

42. ## Pre-Calculus

Which sets of ordered pairs represent functions from A to B? Explain. A = {a, b, c} and B = {0, 1, 2, 3} A. {(a, 1), (c, 2), (c, 3), (b, 3)} B. {(a, 1), (b, 2), (c, 3)} C. {(1, a), (0, a), (2, c), (3, b)} D. {(c, 0), (b, 0), (a, 3)} I narrowed it down to

43. ## Science

Consider a piece of gold jewelry that weighs 9.50 g and has a volume of 0.685 cm^3 . The jewelry contains only gold and silver, which have densities of 19.3 g/cm^3 and 10.5 g/cm^3, respectively. If the total volume of the jewelry is the sum of the volumes

44. ## Math

The cost of fencing a square field at ₹ 27.50 per metre is ₹55000 . Find the cost of reaping the field at ₹45 per 100 metre² .

45. ## Organic Chem

Outline a separation scheme for isolating pure isopentyl acetate from the reaction mixture.

46. ## chemistry

A sample of 300.0g of drinking wtare is found to cntain 38 mg Pb. What is this concentration in parts per million?

47. ## Science

A 10.0 cm long cylindrical glass tube, sealed at one end, is filled with ethanol. The mass of ethanol needed to fill the tube is found to be 11.82 g . The density of ethanol is 0.789 g/mL. Calculate the inner diameter of the tube in centimeters.

48. ## chemistry

what is the formula of iron III tannate?

49. ## chemistry

according to the data in the merck index,if 1,0g of aspirin is dissolved in 100ml of water at 37,how much aspirin will precipitate out of solution when it is cooled to 25.

50. ## Physics

determine the submerged depth of a cube of steel 0.3m on each side floating in mercury given the specific gravities of steel and mercury as 7.8 and 13.6 respectively.

51. ## criminal law

As a computing investigator for your local sheriff’s department, you have been asked to go with a detective to a local school that received a bomb threat in an anonymous email. The detective already has information from a subpoena sent to the last know

52. ## Algebra 1

A survey was taken of students in math classes to find out how many hours per day students spend on social media. The survey results for the first-, second-, and third-period classes are as follows: First period: 2, 4, 3, 1, 0, 2, 1, 3, 1, 4, 9, 2, 4, 3, 0

53. ## physics

A baseball is seen to pass upward by a window 27 m above the street with a vertical speed of 12 m/s. The ball was thrown from the street. (a) What was its initial speed? (b) What altitude does it reach? (c) How long after it was thrown did it pass the

54. ## Calculus

How would I find out what the height of the pile would be after 5 minutes? A machine starts dumping sand at the rate of 20 m3/min, forming a pile in the shape of a cone. The height of the pile is always twice the length of the base diameter. The volume

55. ## Chemistry

Balance this chemical equation. K4Fe(CN)6 + KMnO4 + H2SO4 ---> KHSO4 + Fe2(SO4)3 + MnSO4 + HNO3 + CO2 + H2O

56. ## english

- Computers - English - Foreign Languages - Health - Home Economics - Math - Music - Physical Education - Science - Social Studies GRADE LEVELS - Preschool - Kindergarten - Elementary School - 1st Grade - 2nd Grade - 3rd Grade - 4th Grade - 5th Grade - 6th

57. ## algebra

Jane has 3 times as many cards as peter. the average number of cards owned by the two children is 64. how many cards does jane have?

58. ## Algebra 2

What is the maximum product of two numbers whose sum is 22? What numbers yield this product?

59. ## PHYSICS

An automobile travels 30 km due east on a level road . It then turns due north at an intersection and travels 40km before stopping. What is the the resultant displacement of the car?

60. ## physics

On a cold winter morning, a child sits on a sled resting on smooth ice. When the 9.10 kg sled is pulled with a horizontal force of 36.0 N, it begins to move with an acceleration of 2.10 m/s^2. The 25.0 kg child accelerates too, but with a smaller

61. ## chemistry

draw Lewis Structures for the following FIVE elements. H2S CH2Cl2 NH3 C2H6 CH3OH

62. ## math

Nine more than the quotient of two and a number x.

63. ## Pre-Calculus

If θ represents an angle such that sin2θ = tanθ - cos2θ, then sin θ - cosθ = A. -√2 B. 0 C. 1 D. 2√2 What equation can I use to solve this problem?

64. ## geometry

find the area of the trapezoid whose diagonals are 30 each and height of 18? I spent 2 hrs and I can't figure it out Pls. help 408-887-2612

65. ## Math

Ethel went to the farmers market to buy some eggs (not in a dozen cartons) on the way to the car she accidentally dropped the basket off eggs and all her eggs broke she couldn’t remember the exact number of eggs,but when she picked them out two at a time

66. ## Algebra

a car driver accelerates to a speed of 35 miles per hour and then takes her foot off the gas pedal even though she does not press the brake pedal at any time she eventually rolls to a stop which of the following most likely causes the car to come to a stop

67. ## physics

A spring whose spring constant is 650 N/m is compressed 0.300 m. What speed (in meters/second) can it give to a 0.300 kg ball when released

68. ## physics

A pile driver of mass 1000kg,hits a post 3m below it.It moves the post 10mm.Assuming gravity=10m/s,what is the kinetic energy of the pile driver?

69. ## Statistics

T-Test The article “Does Smoking Cessation Lead to Weight Gain?” described an experiment in which 322 subjects, selected at random from those show successfully participated in a program to quit smoking were weighed at the beginning of the program and

70. ## Math

Angelica ran in a half-marathon. The length of the race was 21.1 km. She ran 1700 m in the first 10 min of the race. In each 10-min interval after the first one, her distance decreased by 4%. How far did she run in the tenth 10-min interval?

71. ## Math

A support wire to the top of a newly planted tree is 15 m long. It forms an angle of 30 degrees to the ground. On the same side of the tree, a second wire is also attached to the top of the tree, but it makes an angle of 45 degrees to the ground. Determine

72. ## Art Study

What does the expression of this superhero mean? Which of the following steps of art critique are you conducting for this type of question? describe analyze present interpret I think B?

73. ## Chemistry

1) What volume of oxygen gas at 28 Celsius and 102 kPa is needed to react completely with 150 g of iron according to the following reaction. Fe(s) + O2 (g) FeO(s) 2) A bunsen burner is lit in a lab that at 24.7 Celcius and 1.07 atm. What mass of water is

74. ## Physics

A spacecraft in orbit around the moon measures its altitude by reflecting a pulsed 10Mz radio signal from the surface. If the spacecraft is 10km high what is the time between the emission of the pulse and the detection of the echo?

75. ## Physics 20

dynamics A curling stone has a mass of 20kg. a curler pushed the stone across the ice to launch it down the rink. a)if the curler starts to move the stone by pushing it with 15N, what is the stones initial acceleration? b)once moving, how much force is

76. ## Pre-Calc

A pilot of an airplane flying at 12,000 feet sights a water tower. The angle of depression to the base of the tower is 25°. What is the length of the line of sight from the plane to the tower?

77. ## chemistry help

Determine the empirical formula for each substance. 1. A dead alkaline battery is found to contain a compund of Mn and O. Its analysis gives 69.6% Mn and 30.4% O. 2. A compound is 38.77% Cl and 61.23 %O. 3. Magnetic iron oxide is 72.4 % iron and 27.6%

78. ## Math

Write and expression that has a value of 100 and the following restrictions: 1. Uses each of the four operations at most once 2. Uses no parentheses 3. Use only the digit 3

79. ## algebra 1

Given the data set (5, 9), (13, 12), (23, 16), which of the following equations best represents a line of best fit? y = three fourthsx − 7 y = four fifthsx + 7 *** y = three over twox + 7 y = two thirdsx − 7

80. ## Biochemistry

1. MES (2-(N-Morpholino)ethanesulfonic acid) is a common buffer used in biochemistry labs to stabilize proteins. The pKa for MES is 6.09. a. What is the pH of 1 liter of a 200 mM MES aqueous solution? Clue: you will need to solve a quadratic equation. (2.5

81. ## Algebra2

The function h(t) = -4.9t^2 + 49t expresses the approximate height, h, in meters, of a ball t seconds after it is launched vertically upward from the ground with an initial velocity of 49 meters per second. After approximately how many seconds will the

82. ## math

A ladder 14 ft long rests against a vertical wall. Let \theta be the angle between the top of the ladder and the wall and let x be the distance from the bottom of the ladder to the wall. If the bottom of the ladder slides away from the wall, how fast does

83. ## Statistics

Maria and Zoe are taking Biology 105 but are in different classes. Maria's class has an average of 78% with a standard deviation of 5% on the midterm, whereas Zoe's class has an average of 83% with a standard deviation of 12%. Assume that scores in both

84. ## Math

Find two quadratic functions, one that opens upward and one that opens downward, whose graphs have the given x-intercepts. (-3, 0), (-1/2, 0)

85. ## physics 2

A thin nonconducting rod is bent to form a semi-circle of radius R. A charge Q is uniformly distributed along the upper half and a charge -Q is uniformly distributed along the lower half, as shown int he sketch at the right.find E vector at P, the center

86. ## physics

A clown is rocking on a rocking chair in the dark. His glowing red nose moves back and forth a distance of 0.42m exactly 30 times a minute in a simple harmonic motion. (a) what is the amplitude of this motion? (b) what is the period of this motion? (c)

87. ## math

A two-digit number is chosen at random.What is the probability that the chosen number is a multiple of 7 ? please answer and explain

88. ## Chemistry

A volume of 70.0mL of aqueous potassium hydroxide(KOH) was titrated against a standard solution of sulfuric acid (H2SO4). What was the molarity of the solution if 19.2mL of 1.50M H2SO4 was needed? The equation is 2KOH+H2SO4->K2SO4+2H20

89. ## science

why is atom electrically neutral

90. ## Math

A car moves along a straight road in such a way that its velocity (in feet per second) at any time t (in seconds) is given by v(x) = 3x sqrt(9-x^2) on an interval of 0,3. Find the distance traveled by the car in 3 seconds.

91. ## Geometry

Find the value of x in the right triangle if the sides given are x, x+1 and 7.

92. ## chem

A 0.158 g sample of magnesium metal reacts completely with 100.0 mL of 1.0 M hydrochloric acid in a coffee cup calorimeter. The temperature of the solution rose from 25.6°C to 32.8°C. What is ∆Hrxn? Assume the specific heat of the solution is 4.184

93. ## Physics

A 150N block rests on a table. The suspended mass has a weight of 73N. a) What is the magnitude of the minimum force of static friction required to hold both blocks at rest? Answer in units of N b)What minimum coeﬃcient of static friction is required to

94. ## Physics

A box is sliding up an incline that makes an angle of 12.0° with respect to the horizontal. The coefficient of kinetic friction between the box and the surface of the incline is 0.180. The initial speed of the box at the bottom of the incline is 1.30 m/s.

95. ## Accounting

What equation was used to get the answer in requirement 3? Consulting to control costs. Requirement 1. Compute Draper's predetermined overhead (OH) allocation rate for 2018. Estimated OH costs / Estimated direct labor costs = Predetermined OH allocation

96. ## math

a man buying a new car can choose among 6 different colors, 3 different steering wheel styles, and 4 different audio packages? what is the total number of different combos he can choose?

97. ## Algebra 2

A rancher is fencing off a rectangular area with a fixed perimeter of 76 m. What dimensions would yield the maximum area? Find the maximum area.

98. ## Physics

A cyclist approaches the bottom of a gradual hill at a speed of 14 m/s. The hill is 4.0 m high, and the cyclist estimates that she is going fast enough to coast up and over it without peddling. Ignoring air resistance and friction, find the speed at which