Question

Stock worth $80 a share dropped in value by 15% on Tuesday, then increased by $7 the next Wednesday and, finally, increased by 12% on Thursday. What was the final price of a share?

Answer 1

Steps

So here are a couple expressions when a value changes by percentage (p = percentage in decimal form and m = original value):

• When decrease: (1 - p)m
• When increase: (1 + p)m

So firstly, the $80 share dropped by 15%. Since this is a decrease, follow the appropriate expression:

$15\%=0.15\\\\(1-0.15)*80\\0.85*80\\68$

On Tuesday, the share went from $80 to $68

Next, on Wednesday the share increased by $7. With this, just add $68 and 7.

$68+7=75$

On Wednesday, the share went from $68 to $75

Lastly, on Thursday the share increased by 12%. Since this is an increase, follow the appropriate expression:

$12\%=0.12\\\\(1+0.12)*75\\1.12*75\\84$

Answer

The final price of the share is $84.