11 Plus Exams Forum

Posted: **Tue Jul 21, 2009 1:08 pm**

Hi

Can someone please help me for this question. Please explain how....

The fish has a head 9cm long. The tail is equal to the size of the head plus one-half the size of the body. The body is the size of the head plus the tail. How long is the fish.

(a) 27cm
(b) 54cm
(c) 63cm
(d) 72cm
(e) 81cm

Thanks for your help.

Rds

Uma

Posted: **Tue Jul 21, 2009 1:20 pm**

(d) is the only one that works.

Or use algebra,,,

Code: Select all

h=9

t = h + b/2    EQ-1

b = h + t      EQ-2

substitute for b in EQ-1

t = h + h/2 + t/2

t/2 = 3h/2

t = 3h

Use 9cm... gives  t=27

b = h + t

gives 

b = 36

Fish = h+b+t

= 9 + 36 + 27

= 72 cm.

But I don't believe you because that's a big fish... did it get away?

Regards
SVE

Posted: **Tue Jul 21, 2009 1:45 pm**

I suppose you could also try and speculate the proportions of the fish...

and work out that...

the proportions that work are...

head 1: body 4: tail 3

h + 4h + 3h

therefore Fish = 8h

But I didn't spot that initially.

Posted: **Tue Jul 21, 2009 7:29 pm**

This is a question from the Junior UKMT challenge ...

Posted: **Tue Jul 21, 2009 7:55 pm**

I used to think I was quite clever. Then I read stuff like this, aimed at TEN YEAR OLDS and shuffle away really rather depressed

11 Plus Exams Forum

help !!!!!

help !!!!!