81 is 18% of what number?
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Answer:
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Step-by-step explanation:
As we know that ,
Mean = sum of the terms/ numbers of terms
But here grouped data is given so , we use the formula
Mean=∑[f. m]/ ∑f
where f is frequency and m is mid point of each height ,
Now first we have to find the mid point of each interval, where
midpoint of each interval = (lower boundary + upper boundary)/2
m1=(150+154)/2 = 152
m2=(155+159)/2= 157,now found other by same formula, for each interval
m3= 162
m4= 167
m5=172 Now we find the midpoint of each interval ,so now
∑[f. m]=f1*m1+f2*m2+f3*m3+f4*m4+f5*m5
now putting the values of each frequency for given interval and midpoint of each interval we will get,
∑[f. m]=456+942+1296+167*x+344 = 167*x+3038
Now find,
∑f=f1+f2+f3+f4+f5
∑f=19+x
Now we have,
∑[f. m]=167*x+3038
∑f=19+x
also given mean height=161.6 cm
putt these values in above equation we get,
161.6=
now solve this ,
161.6(19+x)=167*x+3038
3070.4+161.6*x=167*x+3038
3070.4-3038=167*x-161.6*x
32.4=5.4*x
x=32.4/5.4
<h2>x=6 Ans........</h2>