Can anybody help (please show working)?
Given that a = 4.98, b = 67.8 and c = 22,1, estimate the following without the use of the calculator, correct to 1 significant figure.
b) cube root of 400c + square of (-a) ?

Question

anonymous · Answer

oops I mean 22.1

anonymous · Answer

Hello? Anybody? desperately need an answer?

anonymous · Answer

[400(22.1)]^1/3+(-4.98)^2 ?         4.98^2=.3984+4.482+19.92=24.8004
8840^1/3+24.8004

anonymous · Answer

8840=8*1105
2(1105^1/3)

anonymous · Answer

oh mine. Dn't understand. Not suppose to have decimal as not allowed to use calculator. There is rounding up to whole number to 1 sig. figure

anonymous · Answer

10^3=1000
11^3=1331
10.5^=1157.625
i havent used a calc yet

anonymous · Answer

10.4^3=1124.864
10.3^3=1092.737

anonymous · Answer

727*

anonymous · Answer

don't understand how   4.98^2=.3984+4.482+19.92=24.8004 is derived? Thought just round up all the dec. to 1 sig. fig. first e.g. square of -4.98 = square of -5?

anonymous · Answer

10.35^3=1108.718

anonymous · Answer

no round answers not initial.   that was me multiplying it out and  adding it up like i said havent used a calc yet

anonymous · Answer

round 22.1 to 20, 400*20 = 8000.....the cube root of 8000 is 20......round a to 5....(-5)^2 = 25....add the two #'s and you get 25

anonymous · Answer

if you wanna go that route. im going the get as close as possible still without a calc.

anonymous · Answer

oops...mis-spelled leonard

anonymous · Answer

which would be 20.7+24.8=45.5

anonymous · Answer

you get 45.

anonymous · Answer

25+20

anonymous · Answer

But I thought round 22.1 to 1 significant figure is 22?

anonymous · Answer

so difference of .5. whatever floats your boat

anonymous · Answer

star - is my answer ok for you?

anonymous · Answer

I need to know why rounding 22.1 to 1 sig. figure is 20 and not 22? Also since it is cube root with a negative it would be -20+25=5?

anonymous · Answer

oops 20 + 25 =45

anonymous · Answer

there was no neg with the cube root.  1 sig number would 22.1=20  4.98=5
45=50 etc

anonymous · Answer

i went correct to 1 decimal.

anonymous · Answer

strange the question given was c=-22.1

anonymous · Answer

so cube root of (-20x400)=-20?

anonymous · Answer

then it would b -20 then which would make your final answer be 5

anonymous · Answer

yes

anonymous · Answer

yes

anonymous · Answer

ok tks lots folks

anonymous · Answer

helps to read/write the equation correctly

anonymous · Answer

helps for me not to have typos :)