Porisma

A hint to get started

Combine geometric heights with a weighted class mean

A class has 1616 boys with AP heights and 1010 girls with GP heights. The shortest boy and girl are each 150.0150.0 cm. The tallest boy is 180.0180.0 cm, and the fourth-shortest girl is 157.5157.5 cm.

(i) Show the girls’ common ratio is 1.051/31.05^{1/3} and find the tallest girl’s height to 1 d.p. marks

(ii) Find how many girls are taller than 164.0164.0 cm. marks

(iii) Find the girls’ mean height to 1 d.p. marks

(iv) Find the class mean to 1 d.p. marks

[2013/NYJC/Promo/9]

CJC · Review problems · Question 19

The fourth term has exponent three; weight the final averages by 16 and 10.

Read the worked solution