Answer:
86%
Step-by-step explanation:
Let g represent the mean mark for the 10 girls in the class. Then the mean mark for the class was ...
10g +20(62%) = 30(70%)
g = 3(.7) -2(.62) . . . . . . . . . divide by 10 and subtract 2(.62)
g = .86 = 86%
The mean mark for girls was 86%.
_____
You can do this in your head if you consider it in terms of deviations from the mean. The second equation above can be rewritten and factored as ...
g = 70% +2(70% -62%)
That is, because there are 2 boys for every girl, the girl's score is above the mean by an amount that is 2 times the amount that the boy's score is below the mean. The boys' score is below by 8%, so the girls' score is above by 16%, so is 86%.
Let's draw!
H 1 T
HT 2 HT
HTHT 3 HTHT
HTHTHT 4 HTHTHT
HTHTHTHT 5 HTHTHTHT
HTHTHTHTHT 6 HTHTHTHTHT
You can count the probabilities using this.
HHHHTT
HHHTHT
HHTHHT
HHTHTH
HHHTTH
HTHHHT
HTTHHH
HTHTHH
HTHHTH
THHHHT
THHHTH
THHTHH
THTHHH
TTHHHH
Therefore, I think the probability is 14/64. Not sure so check my work.
14 combinations
64 outcomes (2+4+8+16+32+64 or 2^n)
The answer is 7, your welcome :).
<span>0=10, which is " never true" , and this leads to " no solution" also</span>
Answer:difference of two squares will be
16y^2 -x^2 = (4y -x)(4y +x)
so the second choice
Step-by-step explanation:
