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weqwewe [10]
3 years ago
7

Class 10R sat a test.

Mathematics
2 answers:
uranmaximum [27]3 years ago
7 0

Answer:

86

Step-by-step explanation:

Given that there are 30 students in class 10R and the mean marks for the entire class was 70%. Therefore,

  • total mark of class = 70 x 30 = 2100

Given that there are 20 boys in the class and the mean marks for the boys was 62 %. Therefore,

  • total mark of boys = 62 x 20 = 1240

To calculate the mean mark for the girls we need to find the total number of girl and total mark of girls.

  • total number of girl = 30 - 20 (boys) = 10
  • total mark of girls = total mark of class -  total mark of boys = 2100 - 1240 = 860
  • mean mark for girls = 860 / 10 = 86
Gnesinka [82]3 years ago
5 0

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Write the trigonometric expression sin(sin−1u−tan−1v) as an algebraic expression in u and v. Assume that the variables u and v r
igomit [66]

Answer:

[u – v√(1 – u²)]/√(1 + v²)

Step-by-step explanation:

Let sin^-1(u) = A, therefore sinA = u.

We know that sin(theta) = opposite/hypothenuse

Therefore, sinA = u/1 and u is the opposite side to angle A while 1 is the hypotenuse. Draw an acute triangle placing u opposite to angle A and 1 as the hypotenuse. By Pythagoras theorem the adjacent would be √(1 – u²).

By doing this, it means cosA = adjacent/hypotenuse = √(1 – u²)/1 = √(1 – u²)

Also, let tan^-1(v) = B, therefore tanB = v.

We know that tan(theta) = opposite/adjacent

Therefore, tanB = v/1 and v is the opposite side to angle B while 1 is the adjacent. Draw an acute triangle placing v opposite to angle B and 1 as the adjacent. By Pythagoras theorem the hypothenuse would be √(1 + v²).

Therefore, sinB = opposite/hypotenuse = v/√(1 + v²) and cosB = adjacent/hypotenuse = 1/√(1 + v²)

Now,

sin[sin^–1(u) – tan^–1(v)] =

sin(A – B) =

sinAcosB – sinBcosA =

u[1/√(1 + v²)] – [v/√(1 + v²)][√(1 – u²)] =

[u/√(1 + v²)] – [v√(1 – u²)/√1 + v²)] =

[u – v√(1 – u²)]/√(1 + v²).

8 0
3 years ago
If DF = 170, find the value of x. Then find DE and EF.<br> DE=3x + 20<br> EF=2x + 40
Julli [10]

9514 1404 393

Answer:

  DE = 86

  EF = 84

Step-by-step explanation:

We assume that point E lies on segment DF, so that ...

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  5x = 110 . . . . . . . . . . . . . . . collect terms, subtract 60

  x = 22 . . . . . . . . . . . . divide by 5

  DE = 3×22 +20 = 66 +20 = 86

  EF = 2×22 +40 = 44 +40 = 84

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Step-by-step explanation:

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