Alan

Up thrust from water = 8.84 - 6.86 = 1.98N

Upthrust = volume displaced*water density*g, so volume displaced = 1.98/(1000*10) m^3. (again using g = 10m/s^2) → 0.000198m^3

volume displaced = volume of crown, so

density of crown = mass of crown/volume of crown → (8.84/10)kg/0.000198m^3 → 4464 kg/m^3

Nearest supplied answer is A.

" I don't get it and neither does W/A!!!!!."

That's because you entered r^(n-1) in the numerator of the first term instead of r^n -1

i.e. the "-1" is subtracted from r^n, it isn't subtracted from the n.

Tension in rope when out of water 2.7g ≈ 27N

When weight is submerged in water it experiences an up thrust equal to the weight of water displaced. This reduces the tension in the rope, so the only possible answer of those supplied is D.

(To do the calculation:

Volume of weight = 2.7/2500 m^3. This is the volume of water displaced, hence the weight of water displaced is (2.7/2500)*1000*10 N. (Taking g ≈ 10m/s^2)

Subtract this from the 27N to get something close to 16N)

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In this case the formula is simply FV(n) = $1000*1.02^n,  where n is the number of days

(2% per day is very large! Guest#1's formula would apply if the interest were 2% per annum)

Use the calculator on the home page here to do the calculations.

f(3x) = (3x)^2 - 3*(3x) + 8 → 9x^2 - 9x + 8

Volume = pi*r^2*h/3

r = radius, h = height

.

E = 0.6*12000 + 0.2*0 - 0.2*6000 → 6000

Not quite Asinus!  Slope = (y2- y1)/(x2 - x1)

So, slope = (3-7)/(9-4) = -4/5

Hence, slope of perpendicular = 5/4

60 - 42/14 = 57