这个PHP广告收入分享逻辑是否有效？

I'm adding in my website an Ads revenue sharing system, I built everything, for the ads sharing logic

$random_number = mt_rand(1,10);

if (($random_number >= 1) && ($random_number < 8)) { //gets 1-7 for 70%
$ads = "USER-ADS";
}

if (($random_number >= 8) && ($random_number < 11)) { //gets 8,9, and 10 for 30%
$ads = "ADMIN-ADS";
}

Is this logic is valid?

I want to show the user Ads to 70% of the pageviews, and show my ads for the remaining 30%

The logic looks good. You could use

if ($random_number < 8) {
$ads = 'USER-ADS';
} elseif ($random_number >= 8) {
$ads = 'ADMIN-ADS';
}

as it's a bit more compact and (trivially) faster.