The average of 7 results is 50 , that of the first 3 is 55 and that of the last of 3 is 48. The value of the 4th number is
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1
total of 7 result is = 7×50 = 350
total of first 3 result is 3×55= 165
total of last 3 result is 3×48 = 144
4 th value = total of 7 result - ( total of first 3+total of last 3)
350-(165+144) = 350-309 = 41
Answered by
1
Given sin(A+B)=1
⇒sin(A+B)=sin90
o
(∵sin90
o
=1)
⇒A+B=90
o
…………(1)
Again, cos(A−B)=
3
/2
⇒cos(A−B)=cos30
o
(∵cos30
o
=
3
/2)
⇒A−B=30
o
…………(2)
Adding (1)+(2)
A+B+A−B=90
o
+30
o
⇒2A=120
⇒A=120/2
⇒A=60
Putting A=60
in equation-(2) we get
A−B=30
⇒60
−B=30
⇒60
−30
=B
⇒B=30
∴A=60
;B=30
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