Let the line segment BD be x, then sin A = x/15
or, x = 15sinA
Also
The last option
One month = 5000
Number of months before the spark plugs need to change :
15000 ÷ 5000 = 3
The sparks can last 3 months before it needs to be changed.
Number of times it need to change in a year = 12 ÷ 3 = 4
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Answer : It needs to be change 4 times a year.
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Answer: x=7.7, y=40
3/x = 15/38.5
38.5*3=115.5
115.5/15= 7.7
x=7.7
3/8 = 15/y
15*8=120
120/3= 40
y=40
orrrr you can just easily find the scale factor which is 5, multiply 8 by 5 and get 40. And 38.5/5 which is 7.7
This problem shows 2/5 times 1/3 (Choice C). You can determine this by looking at the number of complete columns that are shaded out of the total number of columns(2/5). The look at how many complete rows are shaded out of the total number of rows shown(1/3). The overlapping part becomes the answer to the multiplication of these 2 fractions.
