Total # Posts: 143
[Update] I think I know what I did wrong. Instead of: (Mass Sample of NaHCO3 / Molar Mass of NaHCO3) * 100 = some value, it should be (Mass Sample of NaHCO3 / Total mass sample of unknown mixture) * 100 = some value. So, (.5517g NaHCO3 / 1.020g of unknown mixture) * 100 = 54....
October 1, 2016
I'm trying to figure out the percent composition of a mixture of an unknown (a combination of NaHCO3 and NaCl). Here's my data: Mass of 150mL of empty beaker: 80.937g Mass of 150mL beaker w/ unknown: 81.957g Mass of 150mL beaker w/ unknown after reaction: 89.126g Mass ...
October 1, 2016
A rocket is fired vertically with an acceleration of 16m/s^2. After time T, the rocket's engine runs out of fuel and it begins to fall freely. The maximum height of the rocket is 940m, what is the minimum value of T?
September 30, 2016
1. What is the value of X in a triangle that has 110° and 30°: 70°, 80°, 90°? 2. A map scale is 1cm to 20km. What is the real distance between two places which are 0.5 apart on the map? 3. When a jeweller sold a ring for 150, he made a profit of 50%. ...
February 2, 2016
1. If a map has a scale of 1cm to 30km, what distance would 1mm represent? 2. If it takes a spacecraft 3 days to travel 250,000 kilometres, what length of time will it take to travel one million kilometres? 3. A publican makes 75 cents on every bottle of beer she sells. How ...
January 27, 2016
1. A music store pays 14 for a CD. At what price must the CD be sold so the shopkeeper can make a profit of 25%? 2. What is the smallest number which can be divided evenly by 500, 600, 1000? 3. A map scale is 1cm to 30km. What is the real distance between two towns which...
January 26, 2016
1. A distance of 1 kilometre is represented on a map by a line 5cm in length. The scale is 1cm to ? m. 2. Value Added Tax at a rate of 20% is added to the price of a washing machine which costs 250 before tax. What will be its price after VAT has been added? 3. How much ...
January 21, 2016
QUESTIONS!! 1.How much would it cost to carpet a room 4m by 3m at 9 per square metre? 2. A television set can be purchased for 299 cash or a deposit of 50 and 12 monthly payments of 25. How much do I save by paying cash? 3. How many thousands in a ...
January 20, 2016
Need help! 1. If a bus is travelling at a speed of 60km/hour,how longlshould it take to travel 10km? 2. Write two whole numbers greater than -5 but less than 0. <------|-----|-----|-----|-----> -10 -5 0 5 *A number line to help you* 3. How much will the lorry driver pay ...
January 11, 2016
Stuck on these questions! 1. Clare is 1.5 metres tall. She is 13cm taller than Michelle. How tall is Michelle? 2. My sister has 40 in her bank account but wrote a cheque for 50 to pay for a new dress. By how much is her account now overdrawn?
January 7, 2016
I am preparing myself for the Entrance Exams so I need help. 1. The middle number of 5 odd numbers is 297. What is the last number? 297 -->-----|-----|-----|-----|-----|-----<-- * Number line* 2. If there is a 10% service change in a restaurant, what is the service ...
January 6, 2016
There is a jar of jelly beans, Dad was hungry so he ate half. Brother wanted some too, so he ate a third, Mom saw brother eating some and ate a fourth. Mom gave 6 to Sister and gave 3 to Grandma. How many Jelly beans were in the jar originally? Justify your answer.
December 14, 2015
maths: Lowest common multiple
Hot dogs are sold in packages of 12 while hot dog buns are sold in packages of 8. Help me! Don't know what to do! (a) How many packs of each should you buy to have the same number of hot dogs and hot dog buns? (b) How many hot dogs in buns would you have?
December 3, 2015
Express the following limit as a definite integral. Show all the steps in your work. Lim as n approaches infinity of (3/n * (n)sigma(I=1) * (1+(3i/n))/(9+(1+(3i/n)^2)). I am utterly lost!
November 27, 2015
When CH3OH at its normal boiling point, does its entropy increase or decrease? Explain. - My opinion The entropy decreases because there is less order due to the less randomness of gas particles favoured when such an element is boiled not at normal boiling point?
November 27, 2015
Stuck on these questions! Help! 1. A ball costing 50 was increased in price by 1%. What was the new price? 2. The perimeter of a swimming pool is 70 metres. If the width is 10 metres, what is the length of the pool? 3. A DVD player can be bought for 250 cash or for...
November 26, 2015
1. A ball costing 50 was increased in price by 1%. What was the new price? 2. The perimeter of a swimming pool is 70 metres. If the width is 10 metres, what is the length of the pool? 3. A DVD player can be bought for 250 cash or for a down payment of 40 and ...
November 26, 2015
Help me on these questions! 1. The teacher's bill for 15 worth of copies and 8 English workbooks was 35. What did each workbook cost? 2. Patrick spent 30% of his money on a football and 60% of it on football boots. If Patrick had 3 left, how much money ...
November 25, 2015
My 1st question is: What is the cost of 1.2kg of putty at 3 a kg? And last question is: A salesman bought a car for 5,000 but later had to sell it for 4,750. How much was his loss?
November 19, 2015
Please help me on these questions. 1. Tom swapped 2/5 og his marbles gor 9 of Martha's. How many has Tom now? I got 15. I'm not sure if it's right. 2. A second-hand book shopmade a profit of 8 bh selling 10 books at 1.90 each. What price 2 was paid for ...
November 16, 2015
Help me and show rough work please . First question:A cup holds 150 millilitres. How many cups of tea can be poured from a full teapot which holds 1.5 litres? 2. Put in order of size, smallest first: 2.2, 2.22, 2.199 3. Mom bought two pillows and paid with a 20 ...
November 11, 2015
Please help me on these problem solving sums. Also show the rough work and answer. First question: If 15% of the children walk to school, 7% cycle to school and 30% come by bus, what percentage come by car ? 2. How much for forty steel nails at 2.50 per 100 ? 3. What is ...
November 10, 2015
Eugene spent half his money in one shop and half of what was left in another shop. He then had1.25. How much had he in the beginning. I am not sure if I got it right so O got 5.00\6.25. So please do show your rough work and answer. Thank You! :D
November 9, 2015
Hey guys I need some help with this question PLZ: A telecommunications company offers a rental deal which costs $30 per month plus 50c per call. a) Find the total cost (T1) for making x calls in a given month b)Find the total cost for making 52 calls in a given month ANOTHER ...
November 4, 2015
Algebra Word Problem
A large hotel finds that it can rent 95 rooms when it charge $100 per room. For each $1 increase in room cost it rents one room less. (Likewise, for each $1 decrease in room cost it rents one room more) What price should it charge in order to maximize the revenue?
April 28, 2015
3 animals need to be chosen. There are 3 tigers, 6 bears, and 4 dogs. Find the probability that: a) 1 tiger, 1 bear, and 1 dog are chosen b) 3 bears are chosen c) no tigers are chosen by the way, we are learning combinations and permutations. Thank you for your help!!!
March 30, 2015
A solution is prepared by dissolving of pure HC2H3O2 and of NaC2H3O2 in of solution (the final volume). (a) What is the pH of the solution? (b) What would the pH of the solution be if of 0.250 M NaOH were added? (c) What would the pH be if of 0.40 M HCl were added to the ...
February 22, 2015
Are there even any physics tutors here???
I don't think it matters when the last question was answered I too noticed that there's a lot of physics questions that go unanswered I think samdata is just asking if there are more physics tutors
February 2, 2015
Use the quadratic formula to solve the equation for x in terms of y and y in terms of x. (Enter your answers as a comma-separated list. If there is no solution, enter NO SOLUTION.) 2x^2 + 7xy + 1 − y^2 = 0 y in terms of x y =
September 15, 2014
Use the quadratic formula to solve the equation for x in terms of y and y in terms of x. (Enter your answers as a comma-separated list. If there is no solution, enter NO SOLUTION.) 2x^2 + 7xy + 1 − y^2 = 0 (a) x in terms of y x = (b) y in terms of x y =
September 14, 2014
A hammer thrower accelerates the hammer (mass = 7.30 kg) from rest within four full turns (revolutions) and releases it at a speed of 21.0 m/s. Assuming a uniform rate of increase in angular velocity and a radius of 0.80 m, calculate the angle of this force with respect to the...
February 2, 2014
What are the individual orders of the reactants involved in the oxidation of methylene blue by ascorbic acid? Rate of reaction= [MB+]^m * [H2A]^n * [HCl]^p What are m, n, and p?
November 26, 2013
If a Signal with a power level of 40 mW is inserted onto a transmission line and the measured power some distance away is 10 mW, calculate the loss of signal strength is decibels.
October 18, 2013
We send a frame of 256 bits. If the probability that a bit changes in transmission is 0.001 and each bit is independent. a. What is the probability that exactly 6 bits change? b. What is the probability that exactly 0 bits change ?
October 18, 2013
1. System A consists of a single ring with 100 stations, one per repeater. System B consists of four 25 stations rings linked by a bridge. If the probability of a link failure is , a repeater failure is , and a bridge failure is , derive an expression for parts (a) to (d). a) ...
October 18, 2013
two trees on a street have the heights of 3 meters and nine metres respectively. at a certain time of day the shorter tree casts a shadow length of five meters how far apart are the trees?
March 13, 2013
You need to move a 129-kg sofa to a different location in the room. It takes a force of 90 N to start it moving. What is the coefficient of static friction between the sofa and the carpet?
November 17, 2012
A staging that weighs Wstaging supports a painter weighing 170 N. The reading on the left scale is 490 N and the reading on the right scale is 220 N. 490 N 220 N What is the weight of the staging? Answer in units of N
November 13, 2012
A circular loop with 30 turns and area of 0.25 m2 rotates at 100 rad/s. The axis of rotation of the loop is perpendicular to the direction of the magnetic field of 0.04 Tesla. What is the maximum emf induced in the loop? 15 V 30 V 45 V 60 V I got 15 V but that doesn't seem...
October 23, 2012
Which of the following is correct for a step-down transformer? Number of turns in the primary coil is less than the number of turns in the secondary coil. Step-down transformer increases the voltage from low value to high value. Number of turns in the primary coil is more than...
October 22, 2012
A point object is acted upon by forces of 4N, 5N and 6N is in equilibrium. IF=f the 6N force is removed, what is the resultant force on the object now? I really want to know how tow find relationship between 3 forces, and is there anything to do with cos rule??? HELPPPPP-.-
October 11, 2012
An aircraft travels through the air with a velocity of 200m/s due east. It is found to be travelling over the ground with a velocity of 220m/s in a direction of 20(degree) south of east.The difference between the two is due to thw wind velocity. What is the wind velocity?
October 10, 2012
A train travels at 3m/s and parallel and very near to the train is a wall the has a slope of 12degrees, the window you see this wall through is .9m high, 2m across, and when you look out you first see the top edge at the lower left of the window, moving towards the top right ...
August 29, 2012
Every sentence in the paragraph below violates some principle of good persuasive writing. Revise the paragraph, following the directions at the end of each sentence; use your imagination where necessary. Type the revised paragraph in the text box provided below. CAUTION: ...
April 12, 2012
Trying to find the power to this ?. A weightlifter lifts a 1250-n barbell 2meters in 3seconds. How much power was used to lift the barbell? Do you have to find the work first??
April 26, 2011
A sample of 12 observations is selected from a normal population for which the population standard deviation is known to be 4. The sample mean is 19. (Round your answers to 3 decimal places.) (a) The standard error of the mean is The 90 percent confidence interval for the ...
March 28, 2011
The National Association for Women in Science asked recent high school grads if they had taken certain science classes. Of those surveyed, 32 said they had taken physics, 51 said they had taken chemistry and 15 said they had taken both. Ten said they had taken neither. How ...
February 20, 2011