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Answers by Michael W.

What is the speed? (answer)

Good evening! This is commonly referred to as a "dirt" problem. D=rt (distance =rate times time). Since the time is the same, rearranging the equation we get t=D/r, so the distance upstream divided by the rate is equal to the distance downstream divided by the rate. The rate downstream...

help with krypton (Kr) and periodic table (answer)

Good evening! Yes, the answer is "a". The mass shown on the periodic table is the average of all isotopes of an element (taking into account the relative abundances of each isotope.   Yes, the answer is "d". If you look at columns, those "families" all...

Is (-1,-3) a solution of 5x+4=-17 and 2x-y-1 (answer)

Good afternoon. You simply plug in the values into the equation and test the inequality.   5(-1) +4(-3) = -17? -5 + -12 =-17 -17=-17   correct   2(-1) - (-3) = 1 -2 - -3 =1 -2+3=1 1=1   correct   So...

acceleration and force (answer)

Force is mass times acceleration. F=ma. The force is the same (presuming no energy is lost converting from the hammer to the stake, which is not precisely true, but usually too small to significantly affect the result). Therefore mass of hammer times acceleration is equal to mass of stake times...

scientific hypothesis (answer)

Hi! The formal definition of a valid scientific hypothesis is an educated explanation of a phenomenon based on prior information, previous knowledge, or other such support. Not to argue with Lewis, but the correct answer (at least from the position of life sciences) is all of the above.   Hypotheses...

x^2+8x-20=0 Solve using any method (answer)

Hi! Since the coefficient of the x^2 is 1 (1x^2), you have a quick method to do this. First identify the factors of 20 in pairs (20*1, 10*2, 5*4)   Now which pair when added or subtracted from each other gives you 8? 20+1=21, 20-1=19, 10+2=12, 10-2=8, 5+4=9, 5-4=1   You...

probability rule 3 (answer)

Presuming these events are all independent and cover all possibilities, this is an exercise in and/or probabilities. Basically keep in mind that and means to multiply, or means to add.   For Christmas to be dry, it could be clear and dry or cloudy and dry: 0.2+0.3 = 0.5   For...

X+1/6=5/6 x= ? (answer)

Good evening! I can help with this. Basically, you need to get the X alone on one side of the equation. So if you subtract 1/6 from the left side of the equation, you have X+1/6-1/6, which becomes X.   What you do to one side of the equation you must do to the other to keep them...

evaluate expression (answer)

When dealing with exponents, you need to remember PEMDAS and step-down. When you multiply factors with exponents, you "step down" when dealing with the exponent and would add them. When you raise a power to another power, you "step down" and multiply exponents.   So,...

Solve algebraically 3x^2/2=2(x-1) (answer)

The first step would be to get rid of any denominators, so multiply both sides of the equation by 2 (what you do to one side of an equation you need to do to the other to maintain equality).   2*(3x^2)/2 = 2*(2(x-1)) and you get 3x^2 = 4(x-1)   Now get rid of the parentheses...

p1=(5,2);p2=4,6) (answer)

These two points are the hypotenuse of a right triangle. You can then make use of Pythagorean theorem to resolve. One leg is the vertical change (y coordinates) and the other is the horizontal change (x coordinates). (y1-y2)^2 + (x1-x2)^2 = c^2   (2-6)^2 + (5-4)^2 = c^2   (4)^2...