A.P.

It has to do with margins for error. Normal heart rate is between 50 and 100 beats per minute. If you measure for less than 20 seconds, the result may be unreliable because to calculate beats per minute, you will need to multiply the result by a number de...

13 years ago

26 letters give you 26 possibilities for the first character. Then, you can combine two digits one hundred ways, if 00 is included. For each one of the 100 combinations of digits, you have 26 possible letters. That means the total number of possibilities...

13 years ago

1km = 1000m She covered the first 3000 meters in 3000/150 = 20 minutes. Since she covered the remaining 3000 meters in 30-20=10 minutes, she must have cycled at 300m/min on average through this stage. Average speed is distance divided by time.

13 years ago

Multiply the first fraction by the denominator of second and vie versa: 4x(x+2)/(x^2-4)+8(x-2)/(x^2-4) =(4x^2+8x+8x+16)/(x^2-4) You can do a little more from here, but this exerise does not yield a very pretty answer. Remember that (a^2)-(b^2) = (a-b)(a+b...

13 years ago

Minor ammendment: I see how the first sentence can be misleading. You multiply both numerator and denominator, not just the numerator.

13 years ago

You can set the number of boys to be x and the number of girls to be y. After a third of the boys leave, you are left with 2/3x. 22 new girls arrive, so you get y+22 Now, you have a system of equations: x+y = 256 2x/3 = y+22 Express y in terms of x in sec...

13 years ago

436. The hundreds must be a four, so the sum of the rest is 13-4=9. Let x be tens. That gives: x+(3+x) = 9 x=6 Find ones: 9-6=3.

13 years ago

Amendment (I seem to be doing that a lot when solving problems in my head) x is, of course 6/2= 3 and represents the tens. Ones are 9-3=6.

13 years ago

In a rectangle, the parallel sides are equal. Thus, x = width 5x/3 = lenght 2x + 2(5x/3) = 200 6x/3 + 10x/3 = 200 16x/3 = 200 x=37.5 Now, you have the short side. To find the long one, multiply by ratio: 37.5 * 5/3 = 62.5 Control: 2*37.5 + 2*62.5 = 200 20...

13 years ago

We know that one nickel is 1/16 inches thick. This means that 16 nickels are: (16*1)/16 =1 So, a stack of 16 nickels is one inch tall. Let us look at the second question: 3 nickels are 1/16 + 1/16 + 1/16 inches. When adding fractions with the same denomin...

13 years ago

I suggest solving this as a system of equations. Let x be the number of Ali's stamps and y be the number of Betty's. x = y+85 x/3 = 2y/3 Now, you can set the x from the first equation in stead of the one in second: (y+85)/3 = 2y/3 y+85 = 2y y=85 Now that...

13 years ago

First, find out what the number is. 12*5/2 = 30 Then, divide by ten. 30/10 = 3

13 years ago

1.0 = 1 1.1 = 1 and 1/10 1.11 = 1 and 11/100 you can also think of the same this way: 1.0 = 1 and 0/100 1.1 = 1 and 10/100 1.11 = 1 and 11/100 thus, 1.11 is the largest of the three. Using this template, you can solve the problem.

13 years ago

The denominator in a fraction tells you how many parts the whole has been divided into. The numerator tells you how many parts this partiular fraction contains. Thus, if you have a whole pie and split it into 12 equal parts, then take 5 of them, you will...

13 years ago

Assuming 0.5 refers to 0.5ft, well, that is the same as 5/10 of a foot. Look at my answers to your other questions and you should be able to solve this without difficulty.

13 years ago

1.99 is less than 2. 2.99 is less than 3. Using this template, this shouldn't prove difficult

13 years ago

I assume by X2 you mean x squared (x^2)? If so, write as ax^2+bx+c=0: x^2 +11x +24 =0 in this case, a=1 because x^2 is not multiplied by a constant, b=11 and c=24. To find the two solutions, use the formula: x= (-b +ã4ac)/(2a) x= (-b -ã4ac)/(2a)

13 years ago

Amendment: The square root sign was not properly processed by this website, it is supposed to say -b+ square root of 4ac for the first solution and -b- square root of 4ac for the second

13 years ago

Second amendment: I see more got lost in formatting - this is what you get for using foreign version of Windows, apparently. x= (-b +- sqrt(b^2 -4ac))/(2a) Let us hope this works now. Sorry about the mess :-)

13 years ago

In an equilateral triangle, all angles are equal. That means, each one is 180/3=60. Correct. A semicircle is indeed a two-dimensional figure.

13 years ago

Let's check: x=1; y=5 5>5*1-2 5>3 Correct.

13 years ago

Are you looking for the slope of a line between said points? If so, find the slope by dividing the difference in y by the difference in x. (y-y0)/(x-x0), where (x0,y0) are the coordinates of the first point and (x,y) are the coordinates of the second. Rem...

13 years ago

Net force is the totla force acting on an object. Remember that forces are vectors, so you have to choose a positive direction, where the vectors will be positive and a negative direction where the vectors will be negative.

13 years ago

Volume is width multiplied by depth multiplied by height. The difference in volume is the new volume minus the old volume. You have all the necessary data - just do the calculations.

13 years ago