The mean (average) height of 4 girls is 152 cm. Melissa joins the group and the mean height of the
group of the 5 girls is now 151.6 cm.
What is Melissa's height?

Melisa's height = 150 cm

Step-by-step explanation:

Initially, we are told there are 4 girls and their average height is 152 cm.

Now, the formula for this average is;

Average height = total sum of heights/number of girls

Thus;

152 = total sum of heights/4

We cross multiply to get;

Total sum of heights = 152 × 4

Total sum of 4 girls height = 608 cm

Now we are told that melissa joins them and the average height of the 5 of them is now 151.6.

Let melissa's height be x.

Thus;

Total height of 5 girls is now; (608 + x)

So, from the formula for average initially;

151.6 = (608 + x)/5

Cross multiply to get;

151.6 × 5 = (608 + x)

758 = 608 + x

Subtract 608 from both sides to get;

758 - 608 = x

x = 150 cm

< coa = 150 ( given)

as ba and bc are tangents

so oc and oa is perpendicular to cb and ab respectively because in circle normal passes through centre

so in quadrilateral oabc

< coa + < oab + < ocb + < abc = 360

150 +90+90 + < abc = 360

330 + < abc = 360

< abc = 360 -330 = 30

so < abc = 30

⭐dhruv⭐

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step-by-step explanation: